Final answer:
When rent is not used to allocate scarce housing, alternative mechanisms such as a lottery or a first-come, first-served system can be utilized, while discrimination is not a valid or lawful method.
Step-by-step explanation:
When rent is not permitted to allocate scarce housing, other mechanisms like a lottery or first-come, first-served may be employed to determine how housing is distributed. A lottery system is random and can be seen as a fair way to allocate housing among a large number of applicants. These mechanisms include a lottery and first-come, first-served. In addition, discrimination can also be a factor in determining who gets access to housing. On the other hand, a first-come, first-served basis rewards those who act quickly to secure housing. Discrimination, although listed as an option, is illegal and unethical and should not be considered a legitimate method for allocating housing.