1.  Choose the correct alternative that will continue the same pattern and replace the question mark in the given series : 6, 11, 21, 36, 56, ?

A. 42
B. 51
C. 81
D. 91

Answer: Option C

Explanation:

The pattern is + 5, + 10, + 15, + 20, ....... So, missing term = 56 + 25 = 81.