Because the shogun’s authority depended on the strength of the samurai class, Yoritomo took steps to ensure the samurai had privileged status. No one could be called a samurai without Yoritomo’s permission. High-ranking samurai were appointed to serve as government advisors and local officials in the provinces. Bushido, the samurai code, demanded that the samurai loyally serve the shogun in whatever capacity the shogun desired. Thus, Samurai lords ruled the villages of Japan, kept law and order, and collected taxes on behalf of the shogun.
Based on this passage, which statement describes the effect of these events?

a. The samurai began to fight one another for power
b. The samurai rebelled against the emperor
c. The samurai refused to recognize the authority of the shogun
d. The samurai became the leading group in Japanese society