Which of the Following Was a Difficulty Faced by the United

Which of the following was a difficulty faced by the United States in asserting its Open Door policy with China?

A) While the U.S.Navy was the strongest in the world,the long distance to China made it difficult to assert its power.
B) The strengthening of the Manchu (Qing) Dynasty was threatening to expel all imperial interests from China.
C) European powers and Japan had already established spheres of influence in China,and without a dominant military it looked as though the United States would be blocked from entry into Chinese markets.
D) The European powers and Japan publicly rebuked Secretary of State Hay for his Open Door Notes.