Suppose a Firm Is Comparing Its Marginal Revenue (MR) and Marginal

Multiple Choice

Suppose a firm is comparing its marginal revenue (MR) and marginal cost (MC) .What circumstances would cause the firm to expand its production?  

A)  if MR is greater than MC 
B)  if MR is less than MC 
C)  if MR equals MC 
D)  if MR equals 0