Explanation:

- Descent: This refers to biological or blood relationships. It describes lineage or ancestry, such as the relationship between parents and their children.

- Affinity: This refers to relationships formed through marriage. A brother-in-law is related by virtue of marriage, not by blood. Hence, this relationship is through affinity.

- Kinship: A broad term that includes both descent and affinity. It describes the connections between members of a family, whether by blood or marriage.

- None of the above: This option implies that the correct description is not listed among the other choices.

Correct Answer: Option 2 - Affinity