2.You plan to have a larger moving window size(移动窗口大小) for the default system-defined moving window baseline because you want to use the adaptive threshold.
你计划增加的移动窗口大小(AWR保留时间必须比他大，dba_hist_wr_control查看awr配置；dba_hist_baseline可以查看移动窗口)
Which statement factors(要素) in this consideration(考虑) while increasing the size of the moving window.?
当增加移动窗口时，需要考虑哪个要素？
A. The collection level for the AWR should be set to BASIC.
AWR配置参数：
BASIC：AWR统计信息的关闭，只收集少量的数据库统计信息。
TYPICAL：默认值，只有部分的统计收集，都是需要监控oracle数据库的典型行为。
ALL：所有可能的统计都被捕捉，并且有操作系统的一些信息，这个级别的捕捉用的较少，比如要更多的sql诊断信息。
B. The moving window size must be less than Undo Retention.
C. The moving window size should be greater than the Automatic Workload Repository (AWR) retention period.
D. The moving window size should be equal to or less than the Automatic Workload Repository (AWR) retention period.
答案：D 比AWR要小。