Which sublime state represents loving-kindness in Buddhism?

The sublime state that represents loving-kindness in Buddhism is metta. Metta is often translated as "loving-kindness," and it is one of the four immeasurables or sublime states in Buddhist thought. This quality embodies unconditional love and benevolence towards all beings, emphasizing a desire for the happiness and well-being of others without any attachment or conditions.

In the context of the other options, karuna represents compassion, upekkha signifies equanimity or mental calmness in the face of life's challenges, and mudita refers to empathetic joy, or the joy in the happiness and success of others. While all four qualities are important and interconnected within Buddhist teachings, metta specifically focuses on the warmth of loving-kindness.