Which of the following letter-number

PMO 51 → SPR 46 → VSU 41 → YVX 36 → ?

Step 1: Observe letters

First letters:
P → S → V → Y
(+3, +3, +3)

Next: Y + 3 = B (after Z, restart from A)

Second letters:
M → P → S → V
(+3, +3, +3)

Next: V + 3 = Y

Third letters:
O → R → U → X
(+3, +3, +3)

Next: X + 3 = A

So letters = BYA

Step 2: Observe numbers

51 → 46 → 41 → 36

Pattern: −5

Next:

36 − 5 = 31

Therefore:
Answer = BYA 31