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.

From the given Option (A),(B),(C) is the same pattern follow given below

(A) 64:100:18

  it is $$ (8)^2:(10)^2: (8+10)$$

$$\Rightarrow (8)^2: (10)^2 : (18)$$ 

(B) 25:16:9

it is $$ (5)^2:(4)^2: (5+4)$$

$$\Rightarrow (5)^2: (4)^2 : (9)$$

(C) 16:64:12

it is $$ (4)^2:(8)^2: (4+8)$$

$$\Rightarrow (4)^2: (8)^2 : (12)$$

But (D) is not satisfied that pattern

(D)81:9:19

$$ (9)^2:(3)^2: (9+3)$$

$$\Rightarrow (9)^2:(3)^2 : (12)$$

therefore Option D is different of given Option 

hence (D)81:9:19 Ans