Which of the following best describes enmity?

Enmity is characterized by a strong and deep-seated hatred or hostility between individuals or groups. This term signifies a profound level of animosity that can stem from various sources such as rivalry, conflict, or historical grievances. It goes beyond mere dislike or resentment, indicating a relationship marred by significant negative feelings.

The other options represent concepts that are fundamentally opposite to enmity. Mutual friendship and strong affection convey positive, uplifting relationships, while indifference suggests a lack of interest or concern, which does not reflect the intensity or emotional depth associated with enmity. Thus, the best descriptor of enmity is indeed the notion of deep-seated hatred, as it encapsulates the essence of the term.