The average annual return over the period 1886-2006 for stocks that comprise the S&P 500 is 11.5%, and the standard deviation of returns is 19.5%. Based on these numbers what is a 95% confidence interval for 2007 returns? A. - 17.5%, 40.5% B. - 27.59%, 50.5% O C. - 13.75%, 25.25% OD. -12.5%, 35.5%