A. It permanently switches to the low_group consumer group if the session exceeds 10,000 I/O requests or 2,500 MB of data transfer.
B. It performs the first 10000 I/O requests or 2,500 MB of data transfer in the LOW-GROUP consumer group,and then switches to the original group.
C. It switches to the LOW_GROUP consumer group if the session exceeds 10000 I/O requests or 2500 MB of data transfer and
returns to the original group after the operation.
D. It switches to the LOW_GROUP consumer group if the session exceeds 10000 I/O requests or 2500 MB of data transfer for queries,
but not for data manipulation language(DML)operations.
答案：（C）
解析：
DBMS_RESOURCE_MANAGER.CREATE_PLAN_DIRECTIVE
switch_for_call,决定是否执行一个操作,因为switch_time, switch_io_megabytes, 或switch_io_reqs参数,
在顶级调用结束之后consumer group是否还原到原来的consumer group.