Rapid-Built Homes specializes in low-cost prefabricated, modular homes that can be erected in a mat-ter of days anywhere in the country. Rapid-Built focuses on entire subdivisions of homes developed by real estate speculators. ModernModular Homes (ModMod) specializes in modular homes designed by architects which can be built anywhere in the country. The buyers usually build the home themselves from kits on their own lots. ModMod sells fewer than 100 house kits per year. ModMod is run by two professors of architecture as a sideline business. According to the "Framework of Competitive Analys-is," we can say that Rapid-Built and ModMod a. are direct mutually-acknowledged competitors. b.have high resource similarity. c.have high market commonality. d.are probably not engaged in intense competitive rivalry.