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 $45 without margin and sell it 1 year later at $50

b) Buy a stock at $45 with 50% margin and sell it 1 year later at $50.

c) Buy a stock at $30 with 75% margin and sell it 1 year later at $45.