If Firms in a Perfectly Competitive Industry Are Earning Positive

If firms in a perfectly competitive industry are earning positive economic profits in the short run,we would expect firms to enter this industry and cause the market supply curve to ________.

A) shift left until price = minimum average total cost
B) shift left until price = minimum average variable cost
C) shift right until price = minimum average total cost
D) shift right until price = minimum average variable cost