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

6 : 1296 :: ? : 6561 :: 5 : 625

9

6 : 1296 :: ? : 6561 :: 5 : 625

The logic followed here is :

Ist number⁴ = IInd number

As

6⁴ = 1296

And

5⁴ =  625

Similarly

? : 6561

9⁴ = 6561