Which action is explicitly prohibited under the Fair Housing Act?

The action that is explicitly prohibited under the Fair Housing Act is refusing to sell or rent to someone based on race. The Fair Housing Act, enacted in 1968, aims to eliminate discrimination in housing based on several protected characteristics, including race, color, national origin, religion, sex, familial status, and disability. This means that any refusal to sell or rent housing based on a person's race is considered a violation of this act.

In contrast, while denying housing based on someone's credit score may not be advisable or equitable, it is not protected by the Fair Housing Act, which focuses on discrimination based on protected categories. Offering lower rental terms to military families is a practice that, while potentially controversial, is not inherently discriminatory under the Fair Housing Act. Lastly, allowing pets only for single tenants does not relate to discrimination based on the protected characteristics outlined in the Fair Housing Act. Hence, the refusal to rent or sell based on race is a clear violation of the law.