As Silver and Copper Mines in Asia Became Exhausted During

As silver and copper mines in Asia became exhausted during the eighteenth century, what policy did the bakufu in Japan adopt?

A) A more open-door policy, seeking other countries with similar mines.
B) A policy of seeking increased trade with Asian countries to finance its silk imports..
C) One that cut out the need for goods that had been previously imported.
D) A more closed policy that encouraged the domestic production of goods that had been previously imported.
E) One that increasingly relied on Korea to provide the means for significant imports.