Answer:
A. Endogamy
Step-by-step explanation:
In sociology, the term endogamy refers to the fact of people marrying with other people that belong to their same group. This can refer to same tribal, religious, ethnic or racial group.
Some people argue that this type of practice helps small communities to keep surviving over long periods of time.
Therefore, when a society has rules that limit marital choices to people within their own social group, such as within their social class or religion, this is known as endogamy.