First, it was a very cool climate in the early fourteenth century when the crop failure happened. Also, irregular lengthy rain patterns killed the crops very fast.
Aristocracy; aristocrats were the rich families often represented by the husbands and fathers
The main purpose of the system is : B. it keeps one person or group in government from having too much power
Before magna Charta, Kings were untouchable by Law and can do whatever they like because the system allowed them to have measurable power within their kingdom.
hope this helps