Question

What government action first allowed American business men to come to China in large numbers

Answer 1

The correct answer is:

Signing of the Burlingame Treaty Apex

The Burlingame Treaty of 1868, signed in Washington was a landmark treaty between the U.S. and Qing China, which ammended the Treaty of Tientsin, ( one of the unequal treaties), which established friendly relations between the two nations, with the United States granting China the status of  most favored nation in trade.