What does "gens" refer to in ancient Roman society?

The term "gens" in ancient Roman society specifically refers to a patrilineal clan sharing a surname, which is the correct interpretation. In this context, a "gens" represented not just a family but a broader social unit identified by common ancestry and usually sharing a family name or nomen. Members of a "gens" would claim descent from a common ancestor and often worked together in social and political contexts. This structure was pivotal in Roman society, influencing various aspects such as inheritance, marriage, and political alliances.

While the other options provide relevant aspects of familial relationships or social structures, they do not encapsulate the specific definition of "gens." For example, a family unit that includes extended relatives touches on kinship but lacks the emphasis on shared ancestry and surname. Similarly, tracing lineage through the maternal line does not align with the patrilineal nature of a "gens," which always operated within a male lineage framework. Lastly, a group formed through marriage alliances could be part of social dynamics but does not directly reflect the fundamental concept of "gens" as a patrilineal clan. Thus, recognizing "gens" as a patrilineal clan sharing a surname provides a clear understanding of its role in ancient Roman society.