A broker is working with a family which is multiracial. The broker only shows properties located in multiracial neighborhoods. Even though the broker thinks they are doing the family a favor, this is violating the Fair Housing Act prohibition against

Redlining involves denying services to residents of certain areas based on racial or ethnic composition, typically affecting access to mortgages and insurance. While it is a serious violation of the Fair Housing Act, it does not directly apply to the broker showing properties only in multiracial neighborhoods, as redlining typically restricts access rather than directing clients.

Disparate treatment refers to treating individuals differently based on their race or other protected characteristics. While the broker's actions may imply a form of disparate treatment, the specific act of only showing properties in multiracial neighborhoods is more accurately classified as steering, which focuses on directing clients toward specific areas based on race.

Blockbusting involves inducing homeowners to sell their properties by instilling fear of the changing racial composition of a neighborhood, often leading to financial loss for those homeowners. Although it is a violation of the Fair Housing Act, it does not apply to the broker's actions of showing properties in multiracial neighborhoods, which is a different practice.