In following number series, two terms have been put within brackets. Choose the appropriate option - Look at this series: 8, 22, 8, 28, 8, . . .What number should come next ?

Answer: D. 34

This is a simple addition series with a random number, 8, interpolated as every other number.
In the series, 6 is added to each number except 8, to arrive at the next number.
In this Series 8 is common number.
Now add 6 with 22 or 28.
22 + 6 = 28
28 + 6 = 34.
So the answer is d = 34.