Explanation:
The database resource manager can help you to limit the number of Parallel Query servers available for a set of users.
Incorrect Answers:

1: The database resource manager cannot control amount of I/O operations to be performed for a set of users.
2: The database resource manager will not help you to limit maximum connection time for a set of users.
3: The database resource manager cannot control the number of concurrent sessions for a set of users.
Oracle 8, DBA Certification Exam Guide, Jason S. Couchman, p. 1149. Chapter 24: Oracle8i New Features Topics

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