An Increase in the Use of Bronze Coins of Various

An increase in the use of bronze coins of various shapes in China during the first millennium B.C.E. indicates which of the following?

A) The Chinese had not yet discovered and adopted iron metallurgy.
B) The Chinese economy was expanding.
C) The lack of central leadership meant that no ruler could impose a single currency.
D) Money from across Afroeurasia circulated throughout China, confirming its place in the international network of trade.