The best answer to the question is "OF."
Explanation:
1. When you know someone and like that person, the relationship is described using the preposition "of." For example, you can say, "I am a friend of Alex," which means you know Alex and have a positive relationship with them.
2. The preposition "of" is used to indicate possession, belonging, or association. In this case, it signifies a connection between two individuals based on knowing each other and having a positive attitude towards one another.
By using the preposition "of" in this context, it conveys the idea that there is a mutual understanding and liking between the two individuals, establishing them as peers in their relationship.
