11.19. Prove the result in equation (11.11). (Hint: For the first part of the relationship, consider (a) a portfolio consisting of a European call plus an amount of cash equal to D K, and (b) a portfolio consisting of an American put option plus one share.)

11.11. A 4-month European call option on a dividend-paying stock is currently selling for $5. The stock price is $64, the strike price is $60, and a dividend of $0.80 is expected in 1 month. The risk-free interest rate is 12% per annum for all maturities. What opportun- ities are there for an arbitrageur?

Please solve 11.19 with the problem 11.11