7. The price of a stock is 20. There is a call and a put option on this stock, both with strike price 18, and both with expiration in one year. The price of the call is 3 and that of the put is 1. The risk-free rate is 1%. Which of the following is correct? a. There is an arbitrage opportunity. To exploit it you should buy the share and the put, sell the call, and take a loan of 18 at the risk-free interest rate. b. There is an arbitrage opportunity. To exploit it you should short sell the share and sell the put, buy the call, and invest 18 at the risk-free interest rate. c. There is not an arbitrage opportunity. d. None of the options is correct