A Stock Produced Returns of 11 Percent, 19 Percent, and 2

A stock produced returns of 11 percent, 19 percent, and 2 percent over three of the past four years, respectively.The arithmetic average for the past four years is 9 percent.What is the standard deviation of the stock's returns for the four-year period?

A) 5.46 percent
B) 8.54 percent
C) 9.09 percent
D) 6.83 percent
E) 7.70 percent