What is the meaning of you have sold a European put option on a stock with maturity 1 year and strike price of $20? a. You have the obligation to buy the stock for $20 at the end of 1 year if the stock is below $20. b. You have the right to sell the stock for $20 at the end of 1 year. c. You have the obligation to sell the stock for $20 at the end of 1 year if the stock is below $20. d. You have the right to sell the stock for $20 anytime during 1 year