SSC CGL 21-August-2017 Reasoning question 8

A series is given, with one term missing. Choose the correct alternative from the given ones that will complete the series.
B, C, E, H, L, ?
Options:
1) Q
2) N
3) O
4) P
Answer: 1
Solution: let A=1, B=2 ...
2, 3, 5, 8, 12

next term would be 12 + 5 = 17(Q)