The author communicates subtext about human beings in this novel by using buck as

D) Hero

Explanation:

The emotions of Buck are depicted with the help of his humanly qualities. Throughout the novel, the speaker talks about his character with the help of describing his emotions, feelings and the insights which involves various contexts and matters. Buck thinks and acts like a human. He feels all the human emotions and overwhelming feelings throughout the novel despite being a dog. He resembles the feelings of the human.

yes this is an analog in my view