Which one of the following SAS programs uses the index to select observations from the data set ONE?

The SAS data set ONE has a variable X on which an index has been created. The data sets ONE and THREE are sorted by X.

Which one of the following SAS programs uses the index to select observations from the data set ONE?
A . data two;
set three;
set one key = X;
run;
B . data two;
set three key = X;
set one;
run;
C . data two;
set one;
set three key = X;
run;
D . data two;
set three;
set one (key = X);
run;

View Answer

Answer: A