The best choice that highlights a main difference between Japanese and European feudalism is:
B. Japanese feudalism was influenced by religions other than Christianity. European feudalism involved the exchange of land for services; Japanese feudalism did not.
While both systems involved a form of land-for-service exchange, the cultural and religious influences, as well as the underlying social structures, differed significantly between the two regions. Japanese feudalism was heavily influenced by Shinto and Buddhism, while European feudalism was intertwined with Christian doctrines. However, it is important to note that the exchange of land for services did exist in both systems, so that aspect of choice B is inaccurate.
If you are looking for a more accurate distinction, a more nuanced understanding of the codes of conduct, like the Bushido code for samurai and the chivalric code for knights, illustrates that they followed different ethical systems, but that fact may not directly denote a fundamental structural difference in the feudal systems themselves.
Given this clarification, none of the choices perfectly encapsulates the differences without inaccuracies.