A producer of fixed proportion goods X and Y (Q= Qx = Qy) has marginal costs and revenues of MC = 10Q, MRx = 200 - 6Qx. MRy = 40 - 4 Qy. The producer should produce how many units?

A Qx=9 , Qy=9

B Qx=9, Qy= 7.5

C Qx = 10, Qy = 10

D Qx = 12, Qy = 12

E Qx = 12, Qy = 10