Step 1: Direct definition check:
Test each pair by asking: 'does one word mean the opposite of the other?'
Step 2: A, B, C fail the test:
In A, B, and C, both words in the pair point in the same semantic direction (achievement, sincerity, intelligence respectively), so none is a true opposite pair.
Step 3: D passes the test:
'Failure' and 'Success' point in opposite directions — one is the negation of the other.
Final Answer:
(D) Failure — Success.