Correct option is A

Given: ZRJ, EUK, JXL, ?, TDN
In first word to second word:
First letter Z (26) + 5 = E (5),
second letter = R (18) + 3 = U (21) ,
third letter J (10) + 1 = k (11)
Logic: first, second and third letter increased by 5, 3 and 1 respectively.
Apply the logic:
For (?): First letter = J + 5 = O, second letter = X + 3 = A, third letter = L + 1 = M
Final Answer: (a) OAM