In which ceremony does a pater familiās acknowledge his child by lifting them in his arms?

The ceremony in which a pater familiās acknowledges his child by lifting them in his arms is known as Susceptiō. This ritual symbolizes the father's acceptance and recognition of the child, marking an important moment in the child's life and establishing their formal status within the family. Susceptiō typically occurs shortly after birth and signifies the child's inclusion in the family unit.

The other ceremonies listed are related to different aspects of family and societal obligations. Impeditio relates to the cutting of the hair of a child, which is a different rite of passage. Votī involves the making of a vow, which pertains to commitments made by individuals rather than acknowledging familial ties. Conspicī does not have the same significance in terms of familial acknowledgment as Susceptiō does, as it is more focused on visibility or exposure rather than formal acknowledgment within a family context. Therefore, the primary purpose and significance of Susceptiō as a ceremony of acceptance differentiate it as the correct answer.