Which line of code is required to initialize the variable Total to 0 in the provided SAS program?

The line of code that initializes the variable Total to 0 in a SAS program must ensure that the variable retains its value throughout the data step iterations. By using the "Retain" statement in conjunction with the assignment of a value, you can ensure that Total is set to 0 for the first iteration and retains that value for subsequent iterations of the data step.

The "Retain Total 0;" line of code serves this purpose effectively. It both initializes Total to 0 and retains that value across iterations of the data step, which is important when processing multiple rows of data where you want the variable to keep its previous value instead of being reset to missing for each new observation.

Other options do not provide the same functionality: simply setting Total with "Total = 0;" in a standard assignment would initialize it but not retain the value through iterations. The condition "IF N = 1 THEN Total = 0;" would also only set the value of Total to 0 for the first observation, but it wouldn’t retain the value in a scenario where later iterations might change it. Similarly, using "Keep Total;" does not initialize or set any value; it just specifies that the variable should be kept in the output dataset.