Which statement is used to specify a condition in a DATA step?

The IF-THEN statement is used in a DATA step to specify a condition that determines the execution of subsequent statements. This allows for conditional processing of data records. When the condition specified in the IF statement evaluates to true, the program can then execute the statements that follow, enabling more complex data manipulations and conditional logic.

For example, you might have a scenario where you only want to perform certain calculations or assign values to variables when specific criteria are met. Using the IF-THEN statement makes this possible, providing flexibility in data handling within the SAS environment.

The other choices do not serve this purpose. The DATA statement is used to begin a DATA step and define a new dataset, while the SET statement is used to read data from an existing dataset into the current DATA step. The LET command is not a valid statement in SAS for this context.