Select the term from among the given options that can replace the question mark (?) in the following series.
NPN23, KQP21, HRR19, ?, BTV15

Given: NPN23, KQP21, HRR19, ?, BTV15

Logic: 1st letter - 3, 2nd letter + 1, 3rd letter + 2 and number - 2 place.

For, 1st letter

N - 3 = K, K - 3 = H, H - 3 = E, E - 3 = B

For, 2nd letter

P + 1 = Q, Q + 1 = R, R + 1 = S, S + 1 = T

For, 3rd letter

N + 2 = P, P + 2 = R, R + 2 = T, T + 2 = V

For, number

23 - 2 = 21, 21 - 2 = 19, 19 - 2 = 17, 17 - 2 = 15

So, the missing term is EST17.

Thus, correct option is (c).