Final answer:
Endogamy refers to the practice of marrying within a certain group to maintain cultural or social continuity, while exogamy dictates marrying outside certain groups to avoid inbreeding and form alliances, making the correct answer 'Endogamy says who one should marry, exogamy says who one should not marry.'
Step-by-step explanation:
The rules of endogamy and exogamy refer to social norms regarding who individuals should and should not marry within a society. Endogamy dictates marrying within a certain group, such as the same social class, ethnicity, or religion, to maintain the cultural or social purity of that group. Conversely, exogamy specifies marrying outside certain groups, such as close kin, to avoid issues like inbreeding and to form alliances with others.
Therefore, the option that best describes these rules is: Endogamy says who one should marry, exogamy says who one should not marry. This reflects the cultural practices where individuals tend to marry within specific social or ethnic groups (endogamy) but avoid marrying those who are considered too closely related (exogamy).