Explanation:
The number of channels allocated will be the maximum degree of parallelization that is used during backup, restore, or recovery operations. Incorrect Answer:
1: A maintenance channel is used as an input AND output channel for a backup or restore Job
2: Allocating a channel allocates not only one RMAN session and one allocated server process.
4: You don’t have to allocate a maintenance channel manually when running a DELETE against a file that is only on disk.
Reference:
OCP Oracle 9i Database: Fundamentals II Exam Guide, Rama Velpuri, p. 224-225
Chapter 9: Oracle Recovery Manager Overview and Configuration

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