Which statement is true regarding the DATA step?

The correct answer is B. The DATA step in SAS is used to read, process, and create data sets. It can read from various sources, not just raw data files but also existing SAS datasets and external databases. It processes the data by executing operations on each observation and can create one or more SAS datasets as output. The other options are incorrect because:

A is incorrect because the DATA step is not limited to reading only raw data files.

C is incorrect because the DATA step can output multiple data sets using the OUTPUT statement.

D is incorrect because the DATA step does not have to be the first step in a program; it can be used anywhere in the program where data processing is required.

References:

SAS 9.4 Language Reference: Concepts, "DATA Step"

SAS documentation on processing data with the DATA step.