Quitar mi eleccin Over the past six years, a stock had annual returns of 12 percent, -3 percent, 2 percent, 274 percent, 9 percent, and 14 percent, respectively. What is the standard deviation of these returns? Seleccione una: a. 6.89 percent b. 5.40 percent c. 6.19 percent d. 6.47 percent e. 7.08 percent