Fill in the blank:

2, 6, 15, 31, 56, ?​​

Given: 2, 6, 15, 31, 56, ?​​

Logic: Numbers are increasing perfect square of natural number from 2.

2 + 4 = 6

6 + 9 = 15

15 + 16 = 31

31 + 25 = 56

Next perfect square: 6²= 36

56 + 36 = 92

So, the missing term is 92.

Thus, correct option is (a).