The following shows the yearly returns of aggressive equity funds for four years: 1999=+5% 2000=+2% 2001=+1% 2002=-4% Assume that this distribution can represent either the population or a sample of aggressive equity funds. Calculate the population and sample standard deviation. Population Standard DeviationSample Standard Deviation（）
A. 2.73% 3.99%
B. 3.09% 4.55%
C. 3.24% 3.74%
