What was the reasoning for creating the fuedal system?

A. gave peasants jobs
B. created knights and a code of chivalry
C.allowed more power for those in charge
D.provided land and work for peasants who worked for noblemen, and in turn the noblemen provided protection for their villages and kingdoms

I GO TO K12 PLS HELPPPP!!!!!!!!!! THIS IS A HISTORY TEST PLS HELP ME!!!!!!!!1