Kelly decided to accept the risk and purchased a high growth stock. Her returns for the past five years are 32 percent, 24 percent, -48 percent, 12 percent, and -9 percent, respectively. What is the standard deviation of these returns? Select one:
a. 23.20 percent
b. 35.46 percent
c. 17.88 percent
d. 32.03 percent
e. 28.39 percent