Which number should come next in this series 10, 17, 26, 37, ?

Option C

Difference between adjacent numbers in series is increasing in a sequence 7,9,11,... so We add 37 and 13 to get 50.

OR

Beginning with 3, each number in the series is a square of the succeeding no. plus 1.

3^2 +1 = 10
4^2 +1 = 17
5^2 +1 = 26
6^2 +1 = 37
7^2 +1 = 50 (missing no.)