What should come in place of the question mark (?) in the given series?
21, 52, 87, 126, 169, ?

Given: 21, 52, 87, 126, 169, ?

Logic: Double difference is + 4 place.

The differences between consecutive terms:

52 − 21 = 31

87 − 52 = 35

126 − 87 = 39

169 − 126 = 43

These differences are increasing by 4 each time:

31 → 35 → 39 → 43 → next: 47

Now, add 47 to the last number:

169 + 47 = 216

So, the missing term is 216.

Thus, correct option is (d).