Given below are four numbers, of which three are alike in some manner and one is different. Choose the odd one.

Logic: Check Prime Numbers.

Option A: 131 → Prime 

Option B: 123 → Not a prime (divisible by 3) 

Option C: 83 → Prime 

Option D: 79 → Prime 

So, 123 is not a prime number (it is divisible by 3).

Thus, the correct option is: (b).