Many economists think that the price of oil has a negative, linear relationship to stock prices. Suppose that the stock market has a base value of 5,000 points even when oil is free or the price of oil is zero. Years later, economists realize that the actual base value of the stock market when oil is free is 7,500. Which of the following describes the change in the graphical representation of stock market value and oil prices?

a. The y-intercept would increase by 50%

b. The slope would decrease

c. The y-intercept would increase by 150%

d. Both a and b