For Consumers, Goods a and B Are Complementary Goods

For consumers, goods A and B are complementary goods. The cost of a resource used in the production of A decreases. As a result,

A) the equilibrium prices of both A and B will fall.
B) the equilibrium price of B will fall and the equilibrium price of A will rise.
C) the equilibrium prices of both A and B will rise.
D) the equilibrium price of B will rise and the equilibrium price of A will fall.