Question

Medieval society began to break down before the Crusades because
a. nobles owned all the land and the houses
b. jealousies arose between nobles of various villages
c. the class system
d. each village was self-contained

Answer 1

Medieval society began to break down before the Crusades because "a. nobles owned all the land and the houses". This led to no social mobility for the peasants. 

Answer 2

The answer is actually B. jealousies arose between nobles of various villages, because of those jealousies it made the middle-class merchants question the authority of the landholders, and the serfs moved to larger cities to work in factories or to become involved in trade, and this led to the breaking down of Medieval life. Mistrust and petty jealousies arose among the landlords, or nobles, and eventually led to the breakdown of medieval society.