Which best describes the tokugawa shogunate and its policies?
a. a dynasty established by ieyasu after he defeated his rivals that increased trade with foreign nations to enhance cultural exchange
b. a dynasty established by samurai that sought to limit trade with foreign nations in order to boost the economy and create national unity
c. a dynasty created when ieyasu united japan, and that later closed off trade to limit western influence on japanese culture
d. a dynasty created after the shogun defeated kublai khan that greatly limited international trade