Consider an economy with two types of firms, S and I. S firms always move together, but I firms move independently of each other. For both types of firms there is a 20% probability that the firm will have a 20% reum and a 80% probability that the firm will have a -30% return. The standard deviation for the return on an individual firm is closest to O A 10% OB. 8% C -20% D. 20%