Assume that Sharon purchases $5,000 worth of a stock. To do so she uses $1,000 of her own money and borrows the remaining $4,000 at a 7.0 percent interest rate. If the stock's value decreases by 10 percent in one year and she has to sell the stock at that time, what is her rate of return?
a. -10 percent
b. -50 percent
c. -78 percent
d. -156 percent