Explanation:
It is possible for the transaction to reuse inactive extents from another undo segment in Automatic Undo Management mode.
Incorrect Answers:
1: It is not possible for the transaction to span different undo segments. It can be assign only to the one undo segments.
3: It is not possible for the transaction to use inactive extents from another undo tablespace. It can only REUSE inactive extents from another undo segment, not from another undo tablespace.
4: It’s not possible for the transaction to extend the undo tablespace, if defined with AUTOEXTENSIBLE set to FALSE.
Reference:
OCP Oracle9i Database: New Features for Administrators, Daniel Benjamin, p. 160-166
Chapter 3: Manageability Enhancements
Oracle 9i New Features, Robert Freeman, p. 53-54
Chapter 2: Oracle9i Architecture Changes

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