Explanation:
If the PGA_AGGREGATE_TARGET initialization parameter is set too low there will be more multipass work area executions than one pass executions.
Incorrect Answers:
1: These statistics are related to the PGA_AGGREGATE_TARGET parameter.
3: If you set the PGA_AGGREGATE_TARGET initialization parameter is set too high there will be more one pass work area executions than multipass executions.
4: It’s not optimal setting because there are many more multipass work area executions than one pass executions.
Reference:
OCP Oracle9i Database: New Features for Administrators, Daniel Benjamin, p. 176-182
Chapter 3: Manageability Enhancements
Oracle 9i New Features, Robert Freeman, p. 19-25
Chapter 1: Oracle9i Database Administration and Management Features

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