Answer:
b. Firm A engaged in predatory pricing.
Step-by-step explanation:
Since Firm A and B are the only two companies that sell mail-order DVD rental subscriptions.
Firm A decided to price its subscriptions below average variable cost thereby causing Firm B to also sell subscriptions below average variable cost, but they went bankrupt and exited the market. Firm A then raised prices by 40% and is currently earning large, positive economic profits.
Based on this information only, an argument can be made that Firm A engaged in predatory pricing.
Predatory pricing is a marketing or pricing strategy that involves lowering the cost of goods and services for a short-term, in order to lure competing firms to lower their price, thus causing them to go bankrupt and exiting from the market.