Explanation:
You must instruct Oracle to gather statistics on the buffer cache by setting the value of the DB_CACHE_ADVICE parameter to ON. The default value for this parameter is OFF. DB_CACHE_ADVICE can take on a third value, READY, which specifies that memory is allocated, but it does not gather statistics. The activity of collecting statistics affects the performance of the system. DB_CACHE_ADVICE is a dynamic parameter and can be changed to ON using ALTER SYSTEM command.
Incorrect Answers:
1: The Advisory is off.
2: The Advisory is off.
3: The memory for the Advisory remains allocated.
Reference:
OCP Oracle9i Database: New Features for Administrators, Daniel Benjamin, p. 180-182
Chapter 3: Manageability Enhancements
Oracle 9i New Features, Robert Freeman, p. 16-17
Chapter 1: Oracle9i Database Administration and Management Features

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