Correct Answer: IRL

Solution : Given:
SHP, RIO, PKN, MNM, ?

To find the next term in the series, subtract the increasing order of the number (starting from 1) from the first letter, add the increasing order of the number (starting from 1) to the second letter, and finally, subtract 1 from the third letter.
First letter of the series→S – 1 = R; R – 2 = P; P – 3 = M; M – 4 = I
Second letter of the series→H + 1 = I; I + 2 = K; K + 3 = N; N + 4 = R
Third letter of the series→P – 1 = O; O – 1 = N; N – 1 = M; M – 1 = L

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