请问下面的这道题目的答案是 SAS log而不是 output window是因为data_null_，不create新的data set吗？ 此外，我还想问一般产生的data set的物理地址在哪里啊？如何判断啊？我貌似也不是很清晰哦？请高手解释一下。谢谢。

The following SAS program is submitted:

data_null_;    set old;    put sales1 sales2;run;

Where is the output written?

A. the SAS log
B. the raw data file that was opened last
C. the SAS output window or an output file
D. the data set mentioned in the DATA statement