How did ming china's relationship with japan differ from its relationship with vietnam?
a. vietnam was outside the sphere of chinese influence, while japan was required to recognize chinese superiority.
b. vietnam was ruled entirely by china, while japan controlled its own government despite chinese occupation.
c. vietnam was infrequently required to give china tributes, while japan was required to give tributes to china more regularly.
d. vietnam successfully resisted chinese attempts at occupation, while japan was never engaged in direct conflict with china.