Q.Consider the following query :
Select E.no,COUNT(*)
FROM Employee E
GROUP BY E.no
If an index on eno is available,the query can be answered by scanning only the index if
A) the index is only hash and clustered
B) the index is only B+ tree and clustered
C)index can be hash or B+ tree and clustered or non-clustered
D)index can be hash or B+ tree and clustered