Explanation:

Her the given number series is 11, 17, 39, 85, ?

11

11 + (3² − 3) = 17

17 + (5² − 3) = 39

39 + (7² − 3) = 85

85 + (9² − 3) = 163

Hence, the next number in the given sequence is 163.

Hence, option 4 is the correct answer.