You are managing a three-Instance RAC database. In the AWR report, you notice a gc current block busy wait event on one

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You are managing a three-Instance RAC database. In the AWR report, you notice a gc current block busy wait event on one of the database Instances, in the cluster top timed events section.What are two possible reasons for this wait event?

A. Access to blocks was delayed as the blocks were pinned In exclusive mode for updates by some sessions.
B. Access to blocks was delayed by log writes on remote Instance.
C. Frequently used select statements are causing high disk Input/output contention.
D. CPU shortages.