In each of the following questions, two numbers are given which follow a certain logical or arithmetic relationship. Identify the same pattern and apply it to find the missing number in the second pair. Choose the correct option from the given alternatives.
40321: 62543 :: 56120 : ?

Given: 40321: 62543 :: 56120 : ?

Logic: Digits are increasing + 2 place.

For, 40321: 62543

4 + 2 = 6, 0 + 2 = 2, 3 + 2 = 5, 2 + 2 = 4, 1 + 2 = 3

Similarly,

56120 : ?

5 + 2 = 7, 6 + 2 = 8, 1 + 2 = 3, 2 + 2 = 4, 0 + 2 = 2

So, 56120 : 78342

Thus, correct option is (b).