- APRT
- BPQR
- CQRS
- DPST
Step-by-Step Solution
The three letters fall back by shrinking amounts — 3, then 2, then 1. M (13) drops to J (10), N (14) drops to L (12) and O (15) drops to N (14). Applied to S (19), T (20) and U (21) this gives P (16), R (18) and T (20). 'PQR' pulls every letter back 3 and 'QRS' pulls every letter back 2, both assuming one fixed step, while 'PST' takes the first letter back 3 and then only 1 for each of the others.
Answer: A) PRT