Select the option that is related to the fifth number in the same way as the first number is related to the second number and third number is related to fourth number.

19 : 359 :: 17: 287 :: 21 : ?

439

19 : 359 :: 17: 287 :: 21 : ?

The logic followed here is :

Ist number² - 2 = IInd number

As

19 : 359

19² -2

= 361 - 2  = 359

and 17 :  287

17² -2

= 289 - 2  = 287

Smilarly

21 : ?

21² -2

= 441 - 2  = 439