You are querying V$BACKUP_ASYNC_IO to determine which files are the bottleneck during RMAN backups. What columns should you use to identify bottlenecks? (Choose the best answer.)

Answer: D

Explanation: If the ratio of LONG_WAITS to IO_COUNT is large, then this file is likely a source of bottlenecks. A, B, and C are incorrect, because all three of these calculations are not valid indicators of a bottleneck.