The table contains a million rows for zonewise analysis in the DSS system. DML operations areperformed very rarely on the table. You decide to prepare an index on the ZONE column to enhance theperformance of the queries on the ZONE column.  Which type of index would you select in this scenario（）

• A、Bitmap index
• B、Reverse key index
• C、Normal B-Tree index
• D、Function-based index