Correct Answer: 15 – 41

Solution : Let’s check the options –
First option: 34 – 43 ; Reversing the digits of 34 leads to the number 43.
Second option: 57 – 75 ; Reversing the digits of 57 leads to the number 75.
Third option: 12 – 21 ; Reversing the digits of 12 leads to 21
Fourth option: 15 – 41 ; Reversing the digits of 15 leads to 51 ≠ 41

So, the fourth option is different from the other three options because on reversing the first number, the number formed is 51 instead of 41. Hence, the fourth option is correct.