Which statement is primarily used to read data into SAS?

The DATA step is primarily used in SAS for reading data into the software. This step allows users to create datasets, manipulate data, and perform calculations or transformations on the data as it's being read in. When utilizing the DATA step, users can specify how to import data from various sources, such as raw data files or existing datasets, and can also define new variables or modify existing ones.

The DATA step not only reads the data but also gives users a great deal of control over the data input process, including how to handle missing values and data types. It serves as a foundational component of data preparation in SAS, enabling analysts to set the stage for further analysis or reporting.

Other options are associated with different purposes in SAS. PROC SORT is specifically used for sorting datasets; PROC PRINT is intended for displaying data in the output; and the MERGE statement is used to combine multiple datasets after they have already been read in. Each of these has its own specific functionality but does not fulfill the primary role of reading data into SAS as the DATA step does.