Answer:
D. Both A and B. Using a variety of different antibiotics and reducing the usage of antibiotics can help to slow down the rate at which bacteria evolve antibiotic resistance. This is because, when exposed to the same antibiotics, bacteria can quickly become resistant. By using a variety of different antibiotics, the chances of bacteria becoming resistant is decreased, and by reducing the usage of antibiotics, it limits the selection pressure on the bacteria and reduces the chance of antibiotic resistance developing.