You have two datasets in your work library, "a" and "b". Dataset "a" contains 3000 observations and dataset "b" contains 1400 observations for a subset of dataset "a" (all ID records in dataset "b" are also in dataset "a") The variables that exist in dataset "a" are: ID, prelim, location, attempt. The variables that exist in dataset "b" are; ID, grade, subject, adviser. If you used the following SAS steps, how many observations would exist in dataset "testMerged"? proc sort data-a out-a; by id run, proc sort data-b out-b; by id; run, data testMerged; merge a(in-ina) b(in-inb); by id if a then output; if b; run, Select one: O a. 3000 b. 1400 O C. The dataset "testMerged" will not exist. O d. 0 O e. 1600 F. 4400