Lets answer this by parts: 1) There is a peasant class in Japanese Bushido, a warrior class called samurais and the noble class. The thing is that the peasants feed the samurai and they protect the peasants and the nobles.The nobles give lands to the samurais as a reward. The base for the Bushido is the Honor. 2) The main elements of the European chivalry are War, Religion and love for women and 3) Because Bushido and Chivalry were aristocratic elites codes the elements that would work well would be a code of conduct, Christianity and a Vision
This answer would be A. school history (aka hell history)
The first one is that right
This is not true! There are many other such factors.
One of them is similar to food: the availability of water.
Other is also natural disasters: tsunamis, earthquakes... they also limit population from time to time. Similarly diseases such as Aids.