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

	Year	Return
	2005	25%
	2004	-10
	2003	30

a.	21.79%
b.	23.87%
c.	20.10%
d.	27.54%
e.	25.18%