The answer is a damaged or scratched drum unit. This is the correct choice because the drum is the photosensitive component that transfers toner onto the paper; any physical defect on its surface will cause toner to be deposited in a continuous vertical line with each rotation, producing the consistent black streaks you see. On the CompTIA A+ Core 1 220-1201 exam, this question tests your understanding of the laser printing process and common image-quality defects—a frequent trap is confusing drum issues with a dirty fuser or corona wire, but remember that fuser problems typically cause smudging or ghosting, not sharp, repeating vertical streaks. A solid memory tip is to think of the drum as a rolling stamp: if the stamp has a scratch, every print will show that same line.
220-1201 Printers Practice Question
This 220-1201 practice question tests your understanding of printers. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 reports that their laser printer is producing pages with vertical black streaks. The streaks appear consistently in the same location on every page. Which printer component is most likely causing this issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Drum unit
Vertical black streaks on a laser printer page are typically caused by a scratched or damaged drum. The drum transfers toner to the paper, and any defect will repeat with each rotation. Cleaning or replacing the drum assembly usually resolves this issue.
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.
✗
Fuser assembly
Why it's wrong here
A faulty fuser usually causes toner smudging or paper jams, not consistent vertical streaks.
✗
Toner cartridge
Why it's wrong here
A leaking toner cartridge can cause random toner spots, but not consistent vertical streaks in the same location.
✓
Drum unit
Why this is correct
A scratched or damaged drum will cause the same defect to repeat on every page, resulting in vertical streaks.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Pickup roller
Why it's wrong here
Faulty pickup rollers cause paper feed issues like jams or misfeeds, not print quality defects like streaks.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 220-1201 question in full detail.
Identify which 220-1201 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Printers — This question tests Printers — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Drum unit — Vertical black streaks on a laser printer page are typically caused by a scratched or damaged drum. The drum transfers toner to the paper, and any defect will repeat with each rotation. Cleaning or replacing the drum assembly usually resolves this issue.
What should I do if I get this 220-1201 question wrong?
Identify which 220-1201 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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