A. ABB
B. BCC
C. CCCDDDD
D. DDDEEEEE
E. BBCCC
Explanation:
In each of the groups ABB, CCCDDDD, BBCCC and DDDDEEEEE, only two letters of the alphabet are used and each letter is written as many times as its place value in the alphabet.
This pattern is not followed in the group BCC.