Which of the following would offer the best return on investment and explain why? Assume that you buy $6,000 in stock in all three cases. Please ignore interest and transaction costs in all your calculations. You have to show the calculation. a. Buy a stock at $80 without margin and sell it 1 year later at $85. b. Buy a stock at $55 with 50% margin and sell it 1 year later at $60. c. Buy a stock at $35 with 75% margin and sell it 1 year later at $40.