A stock is currently trading at $50. A one-year at-the-money put costs $10. The stock price at the end of one year can be equally likely to be one of the following three values: {20, 50, 80}. What is the expected one-year return of a protective put portfolio?
(a) -16:67%
(b) 0%
(c) +16:67%
(d) +50%