The correct answer is (b).
Nagananda is a Sanskrit play written by Emperor Harshavardhana of Kannauj in the 7th century CE. It is about the love between a prince, Jimutavahana, and a naga princess, Nagasena. The play is a Buddhist allegory, and Jimutavahana represents the bodhisattva Avalokiteshvara, who is the embodiment of compassion. Nagasena represents the human world, which is full of suffering. The play tells the story of how Avalokiteshvara comes to the human world to save it from suffering.
Manjushri is a bodhisattva who is often depicted as a young man holding a sword in one hand and a lotus flower in the other. He is the bodhisattva of wisdom and learning.
Vajrapani is a bodhisattva who is often depicted as a fierce warrior with a vajra in his hand. He is the bodhisattva of power and protection.
Avalokiteshvara is a bodhisattva who is often depicted as a compassionate being with a thousand arms and eyes. He is the bodhisattva of compassion and mercy.