单项选择题

A.Optimizer statistics are collected automatically.
B.Only timed operating system (OS) statistics and plan execution statistics are collected.
C.The snapshots for the Automatic Workload Repository (AWR) are not generated automatically.
D.Snapshots cannot be collected manually by using the DBMS_WORKLOAD_REPOSITORY package.
E.The Oracle server dynamically generates the necessary statistics on tables as part of query optimization.