Which animal rights activist protested animal cruelty and research in "A Dog's Tale"?

The correct answer is Mark Twain, who is known for his story "A Dog's Tale." In this narrative, Twain explores themes of animal rights and protests against the cruelty inflicted on animals, particularly in the context of research and experimentation. He uses storytelling to highlight the emotional experiences of a dog, prompting readers to reflect on the ethical treatment of animals. Twain’s work often satirizes societal issues, and in "A Dog's Tale," he employs this technique to advocate for humane treatment and critique the exploitation of animals. This aligns with his broader literary themes of compassion and social justice, making him a fitting choice for an advocate of animal rights in his literary works.

The other figures listed have not specifically focused on animal rights in such a direct and emotionally engaging way through their writings. Their contributions to literature and society, while significant, do not include the same emphasis on the particular issues raised by Twain regarding animal welfare.