The average annual retum over the period 1886-2006 for stocks that comprise the S&P 500 is 10.5%, and the standard deviation of returns is 19%. Based on these numbers what is a 95% confidence interval for 2007 retums? OA -12.5% 33.5% OB.-27.5%, 48.5% O C. - 17.5%, 38.5% OD. - 13.75% 24.25%