Correct Answer: GPDJ

Solution : Given:
OTLN, MSJM, KRHL, IQFK,?

In the above-given series, subtract 2 from the place value of the first and third letters, and 1 from the place value of the second and fourth letters of each term to get the next term.
First letter of the series→O – 2 = M; M – 2 = K; K – 2 = I; I – 2 = G
Second letter of the series→T – 1 = S; S – 1 = R; R – 1 = Q; Q – 1 = P
Third letter of the series→L – 2 = J; J – 2 = H; H – 2 = F; F – 2 = D
Fourth letter of the series→N – 1 = M; M – 1 = L; L – 1 = K; K – 1 = J

So, GPDJ is the missing term of the series. Hence, the third option is correct.