In the arithmetic series -5, -3, -1, 1, _____, the nth term is 15. What is the value of n?

-5, -3, -1, 1, …

First term (a) = -5
Common difference (d) = 2

Formula used:
aₙ = a + (n − 1)d

Given: aₙ = 15

15 = -5 + (n − 1) × 2
15 = -5 + 2n − 2
15 = 2n − 7
2n = 22
n = 11 

Thus, correct option is (b).