You are a DBA of your company. You created a database named SALES on an Oracle 10g instance. You have defined an index named INDEX1 on the database table named INVENTORY. Users are complaining that queries accessing the INVENTORY table are running slow. Upon investigation you determine that the tablespace where the index is located is experiencing high I/O and you decide to relocate the index to another tablespace. Which of these will be the best way to accomplish this objective？（）

A. Rebuild the index.
B. Coalesce the index.
C. Drop and re-create the index in the new tablespace.
D. Relocate the index using the ALTER INDE..MOVE statement.