Which of the Following Became a Major Trade Dispute Between

Which of the following became a major trade dispute between the U.S. and China?

A) Beijing's imposition of higher tariffs on U.S. agricultural exports to China.
B) U.S. unwillingness to permit China to join the World Trade Organization.
C) U.S. refusal to recognize Chinese patents.
D) China's ban on the export of rare earth metals.