Quick Answer
The answer is a-b-c. This output is produced because the Python string join method concatenates each element of the provided iterable—in this case, the list `['a', 'b', 'c']`—into a single string, inserting the string on which join is called (the hyphen) as a separator between each element. On the Certified Associate Python Programmer PCAP exam, this question tests your understanding of string methods and iterable handling, specifically that join requires all elements to be strings or a TypeError will be raised. A common trap is confusing join with split or forgetting that join is called on the separator string, not the list itself. To remember, think of the separator as the “glue” that binds the list items together: the glue goes first, then the list in parentheses. A useful mnemonic is “separator dot join list”—the separator leads the operation, just as it leads the final string.
This PCAP practice question tests your understanding of strings. 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.
What is the output of `print('-'.join(['a', 'b', 'c']))`?
a-b-c
Correct string with hyphens.
['a', '-', 'b', '-', 'c']
Why wrong: Join returns a string, not list.
('a', '-', 'b', '-', 'c')
Why wrong: Join returns a string, not tuple.
a,b,c
Why wrong: That would use comma as separator.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
a-b-c
The `join()` method in Python concatenates the elements of an iterable (here, a list of strings) into a single string, using the string on which it is called as the separator. In this case, `'-'.join(['a', 'b', 'c'])` inserts a hyphen between each element, producing the string `'a-b-c'`. The `print()` function then outputs that string without quotes.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
a-b-c
Why this is correct
Correct string with hyphens.
Related concept
Read the scenario before looking for a memorised answer.
['a', '-', 'b', '-', 'c']
Why it's wrong here
Join returns a string, not list.
('a', '-', 'b', '-', 'c')
Why it's wrong here
Join returns a string, not tuple.
a,b,c
Why it's wrong here
That would use comma as separator.
Common exam traps
Python Institute often tests whether candidates understand that `join()` returns a single string, not a list or tuple, and that the separator is placed between elements, not appended at the ends.
Detailed technical explanation
The `str.join()` method is implemented in C (in CPython) and is highly optimized for concatenating many strings, avoiding the quadratic time complexity of repeated `+` concatenation in a loop. It only works with iterables of strings; passing a list containing non-string elements (e.g., integers) raises a `TypeError`. In real-world applications, `join()` is commonly used to build CSV lines, URL query parameters, or file paths from components.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
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FAQ
Strings — This question tests Strings — Read the scenario before looking for a memorised answer..
The correct answer is: a-b-c — The `join()` method in Python concatenates the elements of an iterable (here, a list of strings) into a single string, using the string on which it is called as the separator. In this case, `'-'.join(['a', 'b', 'c'])` inserts a hyphen between each element, producing the string `'a-b-c'`. The `print()` function then outputs that string without quotes.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This PCAP practice question is part of Courseiva's free Python Institute certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCAP exam.
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