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 30% probability that the firm will have a 20% return and a 70% probability that the firm will have a -30% return. What is the expected return for an individual firm?

A. 5%

B. negative 15%

C. negative 9%

D. 15%