Final answer:
Ethnicity is mostly based upon commonality, such as shared language, customs, traditions, and history.
Step-by-step explanation:
The subject of this question is Ethnicity, which falls under the study of Social Studies.
Ethnicity is mostly based upon commonality. Ethnicity refers to a group of people who share a common cultural or national background. It is primarily determined by a shared language, customs, traditions, and history. For example, people with a shared ethnic background may have common beliefs, values, and practices that bring them together as a community.
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