Answer :

The logic in the sequence is --> +2, +2, +3, +3, +4, +4, +5, +5, +6, +6 and so on...

So, the next number in the sequence would be 24+5 = 29

So, the answer is --> c.29
The series is : 1, 3, 5, 8, 11, 15, 19,
We can see the sequence as
1 = 1
3 = 1 + 2
5 = 3 + 2
8 = 5 + 3
11 = 8 + 3
15 = 11 + 4
19 = 15 + 4
so the next should be 19 + 5 = 24
and after that next should be 24 + 5 = 29

So the answer is 29. i.e.  C