Explanation:
The ALTER TABLE ... MODIFY command temporarily doubles the space requirements to support LONG to CLOB or LONG RAW to BLOB migration. It happened because of need to keep temporary converted data.
Incorrect Answers:
1: It doubles the space requirements, not halves them.
3: The ALTER TABLE ... MODIFY command temporarily doubles, not triples, the space requirements to support LONG to CLOB or LONG RAW to BLOB migration.
4: It doubles the space requirements, not quadruples them.
Reference:
OCP Oracle9i Database: New Features for Administrators, Daniel Benjamin, p. 262-263
Chapter 5: Language Enhancements
Oracle 9i New Features, Robert Freeman, p. 147
Chapter 5: Miscellaneous Oracle9i Features and Enhancements

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