Fred Stickwick Produces Fixed Proportion Goods a and B,with Q_A

Fred Stickwick produces fixed proportion goods A and B,with Q_A = Q_B,marginal costs MC,and marginal revenues MR_A and MR_B.If demand for A is greater than demand for B,Fred should only:

A) produce B to the quantity where MR_B = 0.
B) sell B to the quantity where MR_B = 0 if MR_A is still > MC.
C) produce B to the quantity where MR_B = MC.
D) sell B to the quantity where MR_B = MC.
E) produce B to the quantity where MR_B = MR_A.