What does the KEEP= option do in a SAS procedure?

The KEEP= option in a SAS procedure is specifically designed to dictate which variables are to be retained in the output dataset. When you use this option, you can list the variables you want to preserve, and all other variables will be excluded from the output. This can be particularly useful when working with large datasets, as it allows you to focus only on the relevant variables you need for your analysis or reporting without altering the original dataset.

For instance, if your dataset contains many variables but your analysis requires only a subset of those, using the KEEP= option helps streamline your output, making it more manageable and easier to work with. This feature enhances the efficiency of the data management process in SAS and ensures clarity by including only necessary information in your output datasets.

The other options provided do not accurately describe the function of the KEEP= option. Some pertain to different SAS functionalities, such as sorting, formatting, or dataset combination, but they do not relate to the retention of specific variables in the output, which is the core purpose of the KEEP= option.