The odd numbers from 5 to 21 are used to build a 3 by 3 magic square. (In a magic square, the numbers in each row, the numbers in each column, and the numbers on each diagonal have the same sum.) If 5,9 and 17 are placed as shown, what is the value of x?
Answer Choices
A. 7
B. 11
C. 13
D. 15
E. 19