Why Do Domestic Firms and Foreign Countries Find It Difficult

Why do domestic firms and foreign countries find it difficult to interact with U.S. trade policy?

A) Congress has to approve everything, so it is a slow process.
B) The President has to decide what U.S. trade policy will be.
C) No one agency or person is responsible for U.S. trade policy.
D) The USTR conducts U.S. trade policy through constant and slow negotiations.
E) the U.S. has no discernible trade policy.