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

125 : 625 :: 343 : ? :: 221 : 721

(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.)

125 : 625 :: 343 : ? :: 221 : 721

Logic: The difference between each pair is 500

625 - 125 = 500

721 - 221 = 500

Similarly;

343 + 500 = 843

So, the missing number is 843.

Thus, correct option is (d).