Complete the series.
31,29,24,22,17,(….)

Correct option is D

Given: 31, 29, 24, 22, 17, (...)

31 to 29: Subtract 2

31−2=29

29 to 24: Subtract 5

29−5=24

24 to 22: Subtract 2

24−2=22

22 to 17: Subtract 5

22−5=17

It alternates between subtracting 2 and subtracting 5.

Continue the pattern:

From 17, subtract 2 (next in the pattern):

17−2=15

So, the missing number in the series is 15.

The correct answer is (D) 15.