Four pairs of numbers have been given, out of which three are alike in some manner, while one is different. Choose out the odd one.

13 : 56

7 : 23               7 × 4 + 5  =  33

10 : 45             10 × 4 + 5  =  45

13 : 56             13 × 4 + 4  =  56  which is odd

 6 : 29              6 × 4 + 5  =  29

 So, correct answer is option (3).