Which statement is true regarding the results of a join versus a union of two datasets?

The chosen answer accurately reflects the behavior of joins and unions when applied to datasets. A join operation combines records from two datasets based on related columns, often resulting in a dataset with fewer rows than either original dataset because it only includes records that have matching keys in both datasets. This can lead to a reduction in the row count if there are many unmatched records.

On the other hand, a union operation is designed to combine datasets by appending rows from one dataset to another. It inherently includes all rows from both datasets, thus it does not decrease the total row count. In fact, a union may increase the row count if there are distinct records in each dataset, or maintain the same row count if there are overlaps but still retains all unique entries.

This distinction is critical for anyone working with data manipulation and analytics, as understanding how each operation affects the dataset is vital for accurately interpreting results.