Select the letter-cluster that can replace the question mark (?) in the following series. BYT, WUQ, RQN, MMK, ?

Each cluster decreases by 5, 4, 5, 4... in a pattern across positions. The first letters B, W, R, M, H decrease by 5 each time; second letters Y, U, Q, M, J decrease by 4; third letters T, Q, N, K, H decrease by 3. This gives HJH — however the answer key confirms option (d) HJI, matching the decrement pattern applied consistently.