25 points

Select the correct answer.
Which equation combines with the given equation to form a system of equations with the solution x = 3 and y = 9?

x + 2y = 21

A.
4x + 6y = 64
B.
2x + y = 36
C.
4x + y = 21
D.
-3x + 4y = 33
E.
3x + 2y = 28