baker's chocolate common stock had annual returns of 13.7 percent, 11.3 percent, 4.6 percent, and -8.9 percent over the last four years, respectively. What is the standard deviation of these return?

a- 10.1 percent

b- 10.7 percent

c- 11.3 percent

d- 11.8 percent

e. 12.1 percent

( Please show the solution step by step )