- A
A USB-C to USB-A cable.
Why wrong: This cable would not connect to the car's 3.5mm auxiliary input; it is for data or charging.
- B
A Bluetooth FM transmitter.
Why wrong: This would work wirelessly, but the user wants a wired connection to the auxiliary input.
- C
A USB-C to 3.5mm adapter.
This adapter plugs into the phone's USB-C port and provides a 3.5mm jack that can connect to the car's auxiliary input.
- D
A 3.5mm extension cable.
Why wrong: An extension cable requires a 3.5mm source, which the phone does not have without an adapter.
Question 2 of 1,020
USB-C to 3.5mm Adapter for Car Auxiliary Input
This 220-1201 practice question tests your understanding of mobile device accessories. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A user wants to connect their smartphone to a car's stereo system that only has an auxiliary input (3.5mm jack). The smartphone has a USB-C port and no headphone jack. Which accessory is required?
Quick Answer
The correct accessory is a USB-C to 3.5mm adapter. This is necessary because the smartphone outputs digital audio through its USB-C port, while the car’s auxiliary input is an analog 3.5mm jack; the adapter contains a digital-to-analog converter (DAC) that bridges this gap, allowing the stereo to play the phone’s audio. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your understanding of port types and signal conversion, often appearing as a “best solution” question where a Bluetooth receiver is a tempting distractor—but the exam wants the direct wired connection for reliability and zero latency. A common trap is assuming any USB-C cable works, but only an adapter with a built-in DAC handles the analog conversion. Memory tip: think “DAC in the adapter, not in the car” to remember the conversion happens inside the small dongle.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A USB-C to 3.5mm adapter.
The car stereo only has a 3.5mm auxiliary input, so the smartphone's audio output must be converted to analog audio. A USB-C to 3.5mm adapter contains a digital-to-analog converter (DAC) that converts the smartphone's digital audio signal into an analog signal that the car stereo can accept through the 3.5mm jack.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
A USB-C to USB-A cable.
Why it's wrong here
This cable would not connect to the car's 3.5mm auxiliary input; it is for data or charging.
- ✗
A Bluetooth FM transmitter.
Why it's wrong here
This would work wirelessly, but the user wants a wired connection to the auxiliary input.
- ✓
A USB-C to 3.5mm adapter.
Why this is correct
This adapter plugs into the phone's USB-C port and provides a 3.5mm jack that can connect to the car's auxiliary input.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
A 3.5mm extension cable.
Why it's wrong here
An extension cable requires a 3.5mm source, which the phone does not have without an adapter.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The 220-1201 exam often tests the misconception that a simple cable (like a USB-C to USB-A or a 3.5mm extension) can carry analog audio, when in fact the absence of a headphone jack requires an adapter with an integrated DAC to convert digital signals to analog.
Detailed technical explanation
How to think about this question
USB-C does not natively carry analog audio unless the device supports Audio Accessory Mode (which many modern smartphones omit). Therefore, a USB-C to 3.5mm adapter must include an internal DAC chip (e.g., Cirrus Logic or Realtek) to decode digital audio streams (typically I2S or USB Audio Class 1.0/2.0) into analog line-level output. In real-world scenarios, some adapters are passive and rely on the smartphone's internal DAC, but most require an active DAC, and compatibility can vary between devices due to USB host negotiation and power delivery constraints.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 220-1201 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
What to study next
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FAQ
Questions learners often ask
What does this 220-1201 question test?
Mobile Device Accessories — This question tests Mobile Device Accessories — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: A USB-C to 3.5mm adapter. — The car stereo only has a 3.5mm auxiliary input, so the smartphone's audio output must be converted to analog audio. A USB-C to 3.5mm adapter contains a digital-to-analog converter (DAC) that converts the smartphone's digital audio signal into an analog signal that the car stereo can accept through the 3.5mm jack.
What should I do if I get this 220-1201 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more ways this is tested on 220-1201
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A user wants to use a wired headset with their tablet for voice calls, but the tablet only has a single USB-C port and no 3.5mm jack. The headset has a 3.5mm plug. Which accessory should you recommend?
medium- A.A USB-C hub with multiple ports.
- B.A Bluetooth audio adapter for the headset.
- ✓ C.A USB-C to 3.5mm adapter.
- D.A 3.5mm Y-splitter cable.
Why C: Option C is correct because a USB-C to 3.5mm adapter converts the digital audio signal from the USB-C port into an analog signal that the wired headset can use. This adapter typically includes a built-in DAC (Digital-to-Analog Converter) to handle the conversion, enabling voice calls through the tablet's USB-C port without requiring additional power or Bluetooth pairing.
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Last reviewed: Jul 4, 2026
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