A and B Are Substitute Goods, but a and C

Multiple Choice

A and B are substitute goods, but A and C are complementary goods (in consumption) .If the costs of production of A decrease, then the demand for:

A) both B and C will decrease.
B) both B and C will increase.
C) B will increase and the demand for C will decrease.
D) B will decrease and the demand for C will increase.