The correct option is D A family
Usually, family consists of a group of parents and their children living together as a single unit. A tribe is a social division of society consisting families with links such as social, economic, religious, etc. A society is a group of individuals living together who share similar geographic or social territory. A state is a civil government of a nation with a community of people exercising power over specified territory. Option D - a family is the correct answer, as the smallest and first unit which came into existence.