Item 1 of 63 Mark item for review
When attempting to minimize memory usage, the most efficient way to do group processing when using the MEANS procedure is to use:
A. the BY statement.
B. GROUPBY with the NOTSORTED specification.
C. the CLASS statement.
D. multiple WHERE statements.


网上两种说法——A和C，求大神解答

------------------------------------------------------------------------------------------------------

Item 7 of 63 Mark item for review
A quick rule of thumb for the space required to run PROC SORT is:
A. two times the size of the SAS data set being sorted.
B. three times the size of the SAS data set being sorted.
C. four times the size of the SAS data set being sorted.
D. five times the size of the SAS data set being sorted.



网上也是两种说法——A和C，求大神解答

------------------------------------------------------------------------------------------------------


最好可以给出具体解释，万分感激！！！