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 refers to the practice of denying loans or insurance to individuals based on the racial or ethnic composition of their neighborhoods, typically affecting access to housing finance rather than the selection of properties shown to clients. While it is a discriminatory practice, it does not directly relate to the broker's actions of showing properties in specific neighborhoods.

Disparate treatment involves treating individuals differently based on a protected characteristic, such as race, but it is a broader term. The specific act of guiding a family toward certain neighborhoods based on their race is better classified as steering, which is a more defined violation within the context of real estate practices.

Blockbusting involves inducing homeowners to sell their properties at lower prices by creating fear that racial minorities will move into the neighborhood, thus lowering property values. While related to housing discrimination, it does not apply to the situation where a broker is selectively showing properties based on the family's race.