Consider an economy with two types of firms, S and 1.S firms always move together, but I firms move independently of each other. For both types of firms there is a 70% probabily that the firm will havn a 20% return and a 30% probablity that the fem will have a - 30% refurn. The standard devation for the retum on an individual firmt is closest to: A. 9.17% B. 2291% C. 11,465 D. 5%