Question 15 (10 points) Saved In 2007, the price of oil increased, which in tum caused the price of natural gas to rise. This can best be explained by saying that oil and natural gas are: a) Complements and the higher price for oil decreased the supply of natural gas. b) Substistutes and the higher price for oil decreased the supply of natural gas. c) Unrelated and the prices of both products increased because of increased reliance on fossil fuels. d) Complements and the higher price for oil increased the demand for natural gas. e) Substitutes and the higher price for oif increased the demand for natural gas.