Letter series type of questions usually consists of a series of small letters which follow a certain pattern. However, some letters are missing from the series. These missing letters are then given in a proper sequence as one of the alternatives. The candidate is requitred to choose this alternative as the answer.
C B _ _ D _ B A B C C B _ _ 1 2 4 3 _ _ ? ? ? ? a _ a b _ c _ b _ _ _ _
Comparing position of capital letters, numbers and small letters, as we find:
a correspondes to C and 1 corresponds to a. So a and 1 corresponds to C.
b corresponds to A and 2 corresponds to b. So b and 2 corresponds to A.
Also, 4 corresponds to D.
So the remaining number i.e. 3 corresponds to B, So BCCB corresponds to 3, 1, 1, 3.