Final answer:
The correct answer to the student's question about the PROC SORT step is b: the rows are sorted by Salary in descending order and then by Manager_ID also in descending order, assuming 'descending' applies to both variables.
Step-by-step explanation:
The student has asked about a SAS PROC SORT step that includes the code snippet proc sort data= ; out= ; by descending Salary Manager_ID; run;. To determine which statement is true about this step, we need to analyze each statement against what we know about the SAS PROC SORT procedure.
- a. This statement is incorrect because the input table is not overwritten; this would only occur if the OUT= option was not used to specify a different output dataset.
- b. This statement is true. It correctly indicates that the data is sorted in descending order by Salary and then again by Manager_ID in descending order. However, it should be clear that if the 'descending' keyword is not applied to Manager_ID, then only Salary would be in descending order, and Manager_ID would be in ascending order by default.
- c. This statement is incorrect. A semicolon is an appropriate delimiter in a SAS DATA step to separate dataset names and other options.
- d. This statement is incorrect; the sorted table will contain all the columns from the input table, not just those listed in the BY statement.
Therefore, the correct answer to the student's question is option b, indicating that the rows are sorted by Salary in descending order, and then by Manager_ID in descending order (assuming the descending keyword applies to both variables).