Concerning dumg, which of the following is true ?
A. predatory dumg represents the most common form of dumg by U.S firms
B. U.S firms can obtain protection from foreign dumg, even though this protection tends to harm overall U.S welfare
C. dumg can never be a profit-maximizing strategy for U.S firms to pursue
D. U.S firms rarely if ever, engage in distress dumg or persistent dumg