Explanation:
During a query's parse time Oracle9i flags an index as being used in the V$OBJECT_USAGE view. You can query the V$OBJECT_USAGE view to review the index utilization data. If the index has been used within the period of time it was monitored, the USED column within this view will contain a YES value; it will contain a NO otherwise.
Incorrect Answers:
2: During a query's execution time Oracle9i does not flag an index as being used in the V$OBJECT_USAGE view.
3: Oracle9i flags an index as being used in the V$OBJECT_USAGE view during a query's parse time, not during any kind of DML statement execution.
4: Oracle9i flags an index as being used in the V$OBJECT_USAGE view during a query's parse time, not during execution of an INSERT statement.
Reference:
OCP Oracle9i Database: New Features for Administrators, Daniel Benjamin, p. 212-214
Chapter 4: Performance and Scalability Enhancements
Oracle 9i New Features, Robert Freeman, p. 56-57
Chapter 2: Oracle9i Architecture Changes

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