What was not a major cause reason for the decline of feudalism

The decline of feudalism occurred due to a number of events which occurred during the Medieval era of the Middle Ages. The Crusades and travel during the Middle Ages opened new trade options to England. England started to move from land based economy to a money based economy.The Black Death - this reduced the population of England making labor valuable.  The Feudal Levy was unpopular and as time went by Nobles preferred to pay the King rather than to fight and raise troops

the answer is b, encourage free trade

answer; earthquake;