In the following question, four number pairs are given. In each pair the number on left side of (-) is related to the number of the right side of (-) with some Logic/Rule /Relation. Three pairs are similar on basis of same Logic/Rule/Relation. Select the odd one out from the given alternatives. (NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g.13 - Operations on 13 such as adding /subtracting /multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed)

17 - 1006

The logic followed here is :

Sum of ist number digit = Sum of IInd number digit

21 - 1020 

⇒ 2 + 1 =1+ 0 + 2 + 0 

⇒ 3 = 3

17 - 1006

⇒ 1 + 7 =1+ 0 + 0 + 6

⇒ 8 ≠ 7 (odd)

11 - 1010

⇒ 1 + 1 =1+ 0 + 1+ 0 

⇒ 2 = 2

23 - 1022

⇒ 2 + 3 =1+ 0 + 2 + 2

⇒ 5 = 5