What is an explicit output statement in SAS?

An explicit output statement in SAS is crucial for controlling the process of data output to a dataset. When you use an explicit output statement within a DATA step, you're telling SAS precisely when to write a row of data to the output dataset. This statement allows you to decide at which point in the data step to produce the output, enabling more granular control over the data processing and ensuring that only specified observations are written out.

For example, you may want to generate output based on certain conditions or computations reached during the data step. By placing the output statement conditionally within your code, you can manage the dataset's content according to your analysis needs. This ability is vital for creating output datasets that reflect only the desired results derived from your data transformations.

While the other options touch on aspects of data processing in SAS, they don't accurately describe the role of an explicit output statement as it pertains to controlling output timing to datasets. The statement does not inherently define which variables are output, nor does it control automatic output or specify output format directly. Thus, the correct option effectively captures the purpose of an explicit output statement in SAS programming.