From the eighth through the nineteenth century, Japanese imperial power underwent a period of decline. This is sometimes erroneously attributed to a traditional Japanese belief that clan loyalty was always more important than loyalty to the emperor. The explanation is wrong because even as late as the Kamakura period in the thirteenth and fourteenth centuries, local rulers called shoguns claimed that their authority dervied from that of the emperor, and Japanese peasants rarely challenged the shoguns' authority.

Which of the following, if true, would most seriously weaken the argument?

A) Many Japanese followed the shogun because they assumed the shogun was following the will of the emperor.
B) The Kamakura period collapsed in 1333, followed by 200 years of civil war in Japan.
C) The shoguns were members of independent clans and ruled without regard to the emperor's decrees.
D) During the earlier Heian period, from the years 794 to 1185, the power of the shoguns was far less than it was in the 200 years following the Kamakura period.
E) Some historians believe that geography and the system of taxation were more crucial than clan loyalty in undermining imperial power.