This PL-300 practice question tests your understanding of prepare the data. 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.
You have a Power Query transformation that combines data from multiple Excel files in a folder. Each file has a different structure. You need to identify which TWO actions will help standardize the data before combining. (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use the Combine Files function and select a sample file to define the transformation.
Option C is correct because the Combine Files function in Power Query allows you to select a sample file to define a single transformation logic that is then applied to all files in the folder. This is essential when files have different structures, as it standardizes the data by using the sample file's schema as a template, ensuring consistent column names, data types, and transformations across all files.
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.
✗
Filter out rows with null values.
Why it's wrong here
This does not help standardize structure; it only removes data.
✗
Merge all files into one table before cleaning.
Why it's wrong here
Merging without standardization leads to errors; standardize first.
✓
Use the Combine Files function and select a sample file to define the transformation.
Why this is correct
Combine Files uses a sample file to infer the schema and apply transformations to all files.
Related concept
Read the scenario before looking for a memorised answer.
✓
Promote the first row as headers in each file.
Why this is correct
Promoting headers ensures that column names are consistent across files.
Related concept
Read the scenario before looking for a memorised answer.
✗
Remove all columns except the ones you need from a single file.
Why it's wrong here
This does not standardize across files; other files may have different column names.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think cleaning actions like filtering nulls or removing columns from a single file are sufficient to standardize data across multiple files, but they fail to realize that structural differences require a sample-file-based transformation that is consistently applied to all files.
Detailed technical explanation
How to think about this question
The Combine Files function uses Power Query's 'Transform Sample File' step, which generates a function (e.g., 'TransformFile') that is applied to each binary file in the folder. This function leverages the M language's 'Table.Combine' and 'Table.PromoteHeaders' to enforce the sample file's column order and data types, even if other files have extra or missing columns—those are either ignored or result in errors that can be handled with 'Table.SelectColumns' or error handling. In a real-world scenario, if one file has a 'SalesDate' column and another has 'Date', the sample file transformation can rename or map columns using a custom function, ensuring uniformity.
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 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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Prepare the data — This question tests Prepare the data — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use the Combine Files function and select a sample file to define the transformation. — Option C is correct because the Combine Files function in Power Query allows you to select a sample file to define a single transformation logic that is then applied to all files in the folder. This is essential when files have different structures, as it standardizes the data by using the sample file's schema as a template, ensuring consistent column names, data types, and transformations across all files.
What should I do if I get this PL-300 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.
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Question Discussion
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