Final answer:
Exogamy is best defined as marriage rules that mandate marrying outside one's social group. It facilitates alliances between groups, reduces intra-group competition, and is increasingly common in societies valuing individual choice over social conformity.
Step-by-step explanation:
Exogamy is BEST defined as A. rules that dictate marriage outside a group to which a person belongs. This concept is a social arrangement where marriage is allowed only outside a social group, clan, or tribe. It contrasts with endogamy, the practice of marrying within one's social group.
In societies practicing exogamy, it serves various purposes such as fostering alliances and relationships between different groups, reducing competition for mates within a group, and expanding the social network of the individuals involved. For instance, in the United States, individuals typically marry outside of their immediate family (exogamy), adhering to laws and norms against incestuous relationships, which dictate that certain kinship ties are too close for marital or sexual relationships.
The formation of marriages based on love and compatibility, rather than social and economic standing, has led to a rise in exogamous unions in contemporary societies, where emphasis on individual choice is greater. However, social pressures and norms still exist, encouraging endogamy, or marrying within one's social, ethnic, or economic group.