Option b is the correct answer. Gotra is generally a Kinship unit or a Clan. The word first occurs in 10 th 10 th Mandala of Rigveda. The hymn is addressed to the god Indra, and it describes the different gotras and their origins. The word "gotra" is derived from the Sanskrit word "go" meaning "cow" and "tra" meaning "protection". It literally means "cow protection" or "cowherd". In the Vedic context, it refers to a clan or lineage of people who trace their ancestry back to a common ancestor.