 Branches of mainstream economics are also devoted to specific questions concerning growth, finance, employment, agriculture, housing, natural resources, international trade, and so forth. Within orthodox economics, there are also many different approaches, such as agency theory (Jensen and Meckling 1976, Fama 1980), the Chicago school (Becker 1976), or public choice theory (Brennan and Buchanan 1985, Buchanan 1975). These address questions concerning incentives within firms and families and the ways that institutions guide choices.