Under federal Fair Housing law, which of the following is a protected class?

The federal Fair Housing Act (1968, as amended) prohibits discrimination in housing on the basis of race, color, religion, sex, national origin, disability, and familial status (presence of children under 18). HUD has interpreted 'sex' to include gender identity and sexual orientation. Marital status and age are not federally protected in housing contexts, though some state and local laws do protect these classes. Real estate agents must treat all clients equally regardless of protected-class status: showing the same homes, offering the same financing options, providing the same level of service. 'Steering' (directing buyers to or away from certain neighborhoods based on protected-class characteristics) and 'blockbusting' (inducing sales by suggesting protected-class neighbors will move in) are illegal.