Suppose the price of an item in a perfectly competitive market is $3. For a firm in this market, MC = MR at an output of 100 units. The average total cost at this output level is $4 per unit, and TVC is $80. We may conclude that

A) the firm should shut down because TC > TR.
B) the firm should continue to produce because P>AVC.
C) the firm should shut down because its TFC is $320 and its TC is $400.
D) the firm should shut down because other firms will enter the industry as the market is perfectly competitive.