This The average annual return over the period 1926-2009 for the S&P 500 is 12.7%, and the standard deviation of returns is 218% Based on these numbers, what is a 67% confidence nterval for 2010 rolur? OA.-27.3%, 48 3% OB-9.1% 34,5% OC -1.4%, 20 7% OD-273% 552% A