Find the missing number?

Answer: Option B

Logic (Moving-Down):

7122 = 7 + 1 + 2 + 2 = 12.
6521 = 6 + 5 + 2 + 1 = 14.
8332 = 8 + 3 + 3 + 2 = 16.
4743 = 4 + 7 + 4 + 3 = 18.
9911 = 9 + 9 + 1 + 1 = 20.

So, sum of the last oval box = 22.
387x = 3 + 8 + 7 + x = 22.
x = 22 - 18 = 4.
Missing Element = 4.