Returns for the Alcoff Company over the last 3 years are shown below. What's the standard deviation of the firm's returns? (Hint: This is a sample, not a complete population, so the sample standard deviation formula should be used.)

Year	Return
2010	21.00%
2009	12.50%
2008	26.00%

Select the correct answer.

a. 20.87%

b. 20.93%

c. 20.89%

d. 20.91%

e. 20.95%