Explanation:

- Tavazhi:

- A matrilineal lineage or branch within a larger Tharwad, primarily used among Nair and Ezhava communities in Kerala, India.

- Represents the smallest subdivision in these communities.

- Correct Answer: Tavazhi is indeed the smallest unit of a Tharwad.

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- Namabudiri:

- Refers to a subgroup of Brahmins in Kerala.

- They have their own family and social structures, but not related to the concept of Tharwad’s smallest unit.

- Cheri:

- Typically refers to a small neighborhood or settlement, not specific to Tharwad structure.

- Koli:

- A community in India known for their fishing activities.

- Unrelated to the concept of Tharwad in Kerala.