Concept:Find the number that does not follow the common pattern of digits or divisibility.
Explanation:- 231: digits 1,2,3 → sum = 6; divisible by 3.
- 123: digits 1,2,3 → sum = 6; divisible by 3.
- 312: digits 1,2,3 → sum = 6; divisible by 3.
- 124: digits 1,2,4 → sum = 7; not divisible by 3.
Only 124 has a different digit set and does not satisfy the sum or divisibility rule.
Answer:D. 124