Find the missing number?

Answer: Option C

Logic:

Sum of the element in each row = 23.
First Row,
11 + 12 = 23

Second Row,
6 + 13 + 4 = 23

Third Row,
9 + 4 + 5 + 5 = 23

Fourth Row,
19 + 1 + 3 = 23

Fifth Row,
17 + x = 23
x = 23 - 17 = 6
Missing Element = 6.