I think the answer is number 4
Infectious diseases and colonization.
Sorry, I don't have an answer more specifc than that.
The statement that is false about the Tuskegee study is that the U.S. Public Health Services allowed participants to receive effective treatment when penicillin became widely available after World War II. Option C is correct.
Between 1932 and 1972 the U.S. Public Health Service carried out this clinical experiment or study known as Tuskegee aiming to to analyse the natural history of untreated syphilis. It was considered unethical. It was conducted by the Public Health Service along with the Tuskegee University, 600 impoverished, African-American sharecroppers were subjected to this study and it showed that 399 out of them had latent syphilis and 201 did not contract the disease.