Which protected status includes pregnant women, those in the process of adopting children, or becoming custodial parents/guardians of a child?

The correct choice, which pertains to protected status in the context of housing laws, is familial status. This classification includes not only pregnant women but also those who are in the process of adopting children or who are gaining custodial rights over a child. The Fair Housing Act recognizes familial status as a vital category that protects families with children from discrimination in housing. This protection is crucial in ensuring that families can find suitable living arrangements without facing bias based on the family composition, including circumstances like pregnancy or adoption.

While the other statuses mentioned have their own significance—such as elderliness, which relates to protections against discrimination based on age, and national origin, which protects individuals from discrimination due to their country of origin—none of them encompass the specific scenario presented in the question, which centers on parental or custodial status related to children. Therefore, familial status is the only category that accurately reflects the protections associated with pregnancy and guardianship.