ABC Corporation stock is expected to return 25 percent in a boom, 12 percent in a normal economy, and -13 percent in a recession. The probabilities of a boom, normal economy and a recession are 7 percent, 90 percent and 3 percent, respectively. What is the standard deviation of the returns on this stock?

2.15 percent

19.54 percent

5.53 percent

6.23 percent