Which of the following is an example of a simple aggregation?

• A. Filter by date range
• B. Compute the average of all values
• C. Sort rows by location
• D. Sum values of a column for rows where location = 'X' to get a total for that location

Answer: (D)

A simple aggregation is when you reduce a set of values to a single summary using one aggregate function on a defined group. Here, you take values from a column and only consider rows where location equals 'X', then sum those values to get a total for that location. This produces one number that represents the total for that specific group, which is exactly how a straightforward aggregation works.

The other options don’t summarize data in the same way: filtering by a date range narrows the data but doesn’t produce a summarized value, sorting orders rows without aggregating, and averaging all values across the whole dataset gives a single number but without a defined subgroup to summarize.