Due to the existence of a large number of similar, but not identical, substitutes in most communities, the market for chiropractors is best considered:

Respuesta :

Due to the existence of a large number of similar, but not identical, substitutes in most communities, the market for chiropractors is best considered monopolistically competitive. 

A monopolistic competition is when different producers sell products that are differentiated by branding/quality. Since they differentiate in such ways, they are not perfect substitutes for one another.