大家好！我想请教一道SAS认证的关于macro的题:

Which clause allows macro variable creation on a select statement in PROC SQL?
A. INTO
B. SYMPUT
C. AS
D. %MACRO


Answer: D

为什么A是错的呢？
%MACRO又是如何实现allows macro variable creation on PROC SQL SELECT的呢?

谢谢！