Which of the following ensure that it was western europe that rose to become the dominant force in global politics
a. the collapse of the ming dynasty
b. the chinese policy of isolation
c. the expansion of feudalism
d. the failure of the crusades

The most likely answer why Western Europe became so successful in global politics was B - the chinese policy of isolation in my opinion. 

China was a very advanced country which was at the same time extremely powerful and vast, putting it mildly. However, their choice of being an isolationist country made room for the smaller European countries to be at the center stage of world politics.