You want to enable automatic PGA memory management in your database. Which setting is
required to achieve this?
A.
Set MEMORY_TARGET to zero
B.
Set the STATISTICS_LEVEL parameter to BASIC
C.
Set the WORKAREA_SIZE_POLICY parameter to MANUAL
D.
Set the PGA_AGGREGATE_TARGET parameter to nonzero value
D is correct:
https://docs.oracle.com/cd/B28359_01/server.111/b28320/initparams177.htm
Setting PGA_AGGREGATE_TARGET to a nonzero value has the effect of automatically setting the WORKAREA_SIZE_POLICY parameter to AUTO. This means that SQL working areas used by memory-intensive SQL operators (such as sort, group-by, hash-join, bitmap merge, and bitmap create) will be automatically sized. A nonzero value for this parameter is the default since, unless you specify otherwise, Oracle sets it to 20% of the SGA or 10 MB, whichever is greater.