Consider a portfolio manger whose mission is "to maximize annual returns through equity investments in the single-family homebuilding industry." Which is the best opportunity cost investment for this manager? a) Blackstone's Single Family Housing mutual fund, which makes money by purchasing a large number of homes and renting them to families b) The SPY exchange-traded fund, which very closely matches the returns of the S&P 500 stock market index. c) An exchange-traded fund that owns stocks in companies such as DR Horton, Lennar and NVR Inc d) A mutual fund that invests in multi-family rental REITS, such as Post Properties and HMO.