Explanation:
The ALTER TABLE table_name COALESCE statement will reorganize the IOT. The rebuild operation creates a new tree to defragment the index, as opposed to the coalesce operation that coalesces the leaf blocks within the same branch of the tree.
Incorrect Answers:
1: You cannot do this using EXPORT and IMPORT with specified options. There is no INDEX option in EXPORT utility. Only INDEXES option exists.
3: This command can be used to rebuild the secondary index of IOT only.
4: This command is incorrect: you cannot use the ONLINE option that way.
Reference:
OCP Oracle9i Database: New Features for Administrators, Daniel Benjamin, p. 76-78
Chapter 2: Availability Enhancements
Oracle 9i New Features, Robert Freeman, p. 46-53
Chapter 2: Oracle9i Architecture Changes

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