What Loophole Do International Firms Take Advantage of in Circumventing

What loophole do international firms take advantage of in circumventing anti-dumping laws?

A) They modify their products slightly so as not to permit a direct comparison.
B) They use a cash-based accounting method instead of an accrual-based accounting method.
C) They set prices based on their fixed costs instead of their marginal costs.
D) All of the above are true.