Number Series - Verbal and Reasoning

Directions to SolveLook carefully for the pattern, and then choose which pair of numbers comes next.
Q1:

21 25 18 29 33 18

A 43 18

B 41 44

C 37 18

D 37 41

E 38 41

ANS:D - 37 41

This is a simple addition series with a random number, 18, interpolated as every third number. In the series, 4 is added to each number except 18, to arrive at the next number.