The ST_INFO master table has millions of rows that are updated very rarely. It has a STATE_CODE column that contains the value for 25 states. The table is frequently queried on the STATE_CODE column. <br /> Which type of index would you suggest to improve the query performance?()<p> The ST_INFO master table has millions of rows that are updated very rarely. It has a STATE_CODE column that contains the value for 25 states. The table is frequently queried on the STATE_CODE column. <br /> Which type of index would you suggest to improve the query 
A、A.Btree
B、B.bitmap
C、C.reverse key
D、D.function based