During the 1970s the price of oil rose dramatically, which in turn caused the price of coal to increase. This can best be explained by saying that oil and coal are:
A. substitute goods and the higher price for oil increased the demand for coal
B.complementary goods and the higher price for oil decreased the supply of coal.
C. complementary goods and the higher price for oil increased the demand for coal
D. substitute goods and the higher price for oil decreased the supply of coal