Rent control is usually justified on the grounds that it protects moderate- to low-income families from the burden of rapidly rising rents and from eviction if they are unable to pay. It also prevents landlords from reaping windfalls as property values rise. Opponents note that rent controls usually lead to a reduced supply of rental housing and shortages. The proponents of rent controls support them primarily on the grounds of a. externalities. b. efficiency. c. equality. d. cost disease of services.