Which of the following would offer the best return on investment? Assume that you buy $5,000 in stock in all three cases, and ignore interest and transaction costs in all your calculations.

a. Buy a stock at $80 without margin, and sell it 1 year later at $120.

b. Buy a stock at $32 with 50% margin, and sell it 1 year later at $41.

c. Buy a stock at $50 with 75% margin, and sell it 1 year later at $65.