A. The V$PGA_TARGET_ADVICE view shows the predicted cache hit-ratio improvement if you increase PGA_AGGREGATE_TARGET.
B. The V$PGA_TARGET_ADVICE view shows how the V$SQL_WORKAREA histogram will change if you change the value of PGA_AGGREGATE_TARGET.
C. The V$PGA_TARGET_ADVICE_HISTOGRAM view shows how the V$SQL_WORKAREA_HISTOGRAM will change if you switch between Manual and Automatic PGA Memory Management.
D. The V$PGA_TARGET_ADVICE view shows how performance will improve for the different work areas if you switch from Manual to Automatic PGA Memory Management.
答案：（A）
解析：
V$PGA_TARGET_ADVICE和V$PGA_TARGET_ADVICE_HISTOGRAM的说明