Find the missing number?

Answer: Option C

Split the grid in half vertically, to give two columns, 3 squares wide. Working from top to bottom, left then right, and reading each 3 square row as a whole 3 digit number, the columns follow the sequence of square numbers, from 10 to 21.So, last three digit number would be square of 21.

21 * 21 = 441.
Missing Element = 1.