What is required to define a new library reference (libref) in SAS?

To define a new library reference (libref) in SAS, the LIBNAME statement is essential. This statement establishes a connection between SAS and a specific location where data sets are stored, whether on a local machine or on a remote server.

When you use the LIBNAME statement, you specify a name (the libref) that SAS can use to refer to the library in subsequent data steps or procedures. This allows you to easily access and manipulate data sets stored in that library without needing to specify the entire file path each time.

The other options do not serve the purpose of defining a library reference. The SET statement is typically used within a DATA step to read data from an existing data set, not to create a new library reference. Similarly, a DATA step is used for data manipulation and creation of new data sets, and a PROC step is aimed at analyzing or reporting on data sets already defined, but neither of them creates a libref on its own.