(46 - 10) , (42 - 33) , (20 - 38) , (12 - 91)
Option:
Justification: In all other pairs, the different between the two numbers is a multiple of 9.

(46 - 10) , (42 - 33) , (20 - 38) , (12 - 91)
Justification: In all other pairs, the different between the two numbers is a multiple of 9.