Which statement is used to modify SAS data sets in PROC DATASETS?

The statement used to modify SAS data sets in PROC DATASETS is RENAME. This is because the RENAME statement allows you to change the names of variables within a data set without having to create a new data set. It is particularly useful for restructuring datasets or clarifying variable names for better readability and understanding.

In PROC DATASETS, the RENAME statement specifically alters the metadata of a data set by mapping old variable names to new ones. This functionality is essential in data management, especially when preparing datasets for analysis, to ensure that the variable names accurately represent the data they contain.

Other options have distinct functions that do not relate directly to modifying variable names within a dataset. For example, DELETE is used to remove entire datasets or specific observations, while SORT organizes data but does not alter variable names. MERGE combines multiple datasets based on common variables, also without changing names. Therefore, RENAME is uniquely suited for the purpose of modifying variable names in a given dataset in PROC DATASETS.