Calvin's Corner Market, a national chain of grocery stores, was charged with price discrimination under the Robinson-Patman Act. Which of the following defenses may protect Calvin's from liability? O Calvin's was only meeting the price of its competition. O Calvin's charged lower prices because the merchandise was damaged. The price differences were based on legitimate cost differentials. O All of the above are valid defenses under the Robinson-Patman Act. O None of the above Are valid defenses under the Robinson-Patman Act. O (a) and (b) only. O (b) and (c) only