MLS-C01 Exploratory Data Analysis Practice Question
This MLS-C01 practice question tests your understanding of exploratory data analysis. 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.
Exhibit
Refer to the exhibit. Consider the following AWS CLI output from an Amazon Athena query:
QueryExecutionId: "12345678-1234-1234-1234-123456789012"
Query: "SELECT COUNT(*) FROM my_table WHERE col1 IS NULL"
Status: "SUCCEEDED"
ResultConfiguration:
OutputLocation: "s3://my-bucket/athena-results/"
ResultSet:
Rows:
- Data:
- VarCharValue: "_col0"
- Data:
- VarCharValue: "5000"
The exhibit shows the result of an Athena query. What does the value '5000' represent?
Refer to the exhibit. Consider the following AWS CLI output from an Amazon Athena query:
QueryExecutionId: "12345678-1234-1234-1234-123456789012"
Query: "SELECT COUNT(*) FROM my_table WHERE col1 IS NULL"
Status: "SUCCEEDED"
ResultConfiguration:
OutputLocation: "s3://my-bucket/athena-results/"
ResultSet:
Rows:
- Data:
- VarCharValue: "_col0"
- Data:
- VarCharValue: "5000"
A
The total number of rows in the table
Why wrong: The query is counting only NULL rows, not the total.
B
The number of rows where col1 is NULL
The query counts rows with NULL in col1.
C
The number of rows where col1 is not NULL
Why wrong: The query counts NULL rows, not non-NULL.
D
The number of distinct values in col1
Why wrong: The query is a count of NULL rows, not distinct values.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The number of rows where col1 is NULL
Option B is correct because the query counts rows where col1 IS NULL, and the result '5000' is that count. Option A is wrong because the query is not selecting distinct values. Option C is wrong because the query counts NULL rows, not non-NULL. Option D is wrong because total row count was not queried.
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.
✗
The total number of rows in the table
Why it's wrong here
The query is counting only NULL rows, not the total.
✓
The number of rows where col1 is NULL
Why this is correct
The query counts rows with NULL in col1.
Related concept
Read the scenario before looking for a memorised answer.
✗
The number of rows where col1 is not NULL
Why it's wrong here
The query counts NULL rows, not non-NULL.
✗
The number of distinct values in col1
Why it's wrong here
The query is a count of NULL rows, not distinct values.
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 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
Got this wrong? Here's your next step.
Identify which MLS-C01 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.
Exploratory Data Analysis — This question tests Exploratory Data Analysis — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The number of rows where col1 is NULL — Option B is correct because the query counts rows where col1 IS NULL, and the result '5000' is that count. Option A is wrong because the query is not selecting distinct values. Option C is wrong because the query counts NULL rows, not non-NULL. Option D is wrong because total row count was not queried.
What should I do if I get this MLS-C01 question wrong?
Identify which MLS-C01 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.
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 →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This MLS-C01 practice question is part of Courseiva's free Amazon Web Services 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 MLS-C01 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.