The correct answer for who discovered the anti-rabies vaccine is Louis Pasteur (option 3). Although options 1, 2, and 4 were great scientists in their own right, they were not the ones who discovered the anti-rabies vaccine.
Edward Jenner (option 1) is known for developing the smallpox vaccine, not the anti-rabies vaccine. James Lind (option 2) is known for conducting one of the first controlled experiments on scurvy and is often considered the founder of modern clinical trials, but he did not discover the anti-rabies vaccine. Robert Koch (option 4) is known for his work in identifying the causative agents of various diseases, such as tuberculosis and cholera, but he was not responsible for discovering the anti-rabies vaccine either.
Therefore, the correct answer is option 3, Louis Pasteur. Pasteur is renowned for his groundbreaking work in microbiology, including the development of the rabies vaccine. He successfully tested the vaccine on dogs in 1885 and later on humans, significantly reducing the mortality rate associated with rabies.