Explanation:

Fourth option is correct.

The World Homoeopathy Day (WHD) is observed every year on April 10 to pay tribute to Dr. Christian Friedrich Samuel Hahnemann, founder and father of Homeopathy system of medicine. Numerous leading conventional physicians and scientists who have had extremely positive things to say about homeopathy include Sir William Osler (the “father of modern medicine”), Emil Adolph von Behring, MD (the “father of immunology”), Charles Frederick Menninger, MD (founder of the Menninger Clinic), August Bier, MD (the “father of spinal anesthesia”), C. Everett Koop, M.D. (former Surgeon General, U.S.), Brian Josephson, PhD. (Nobel Laureate & Cambridge professor).