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)

1009 - 1018091

The logic followed here Is :

Second number is the square of ist number

1003 - 1006009   ⇒  1003² = 1006009

1009 - 1018091 ⇒  1009² = 1018081 ≠ 1018091

1007 - 1014049   ⇒ 1007² = 1014049

1001 - 1002001   ⇒ 1001² =  1002001