chickens that naturally make the antibiotics microbes that are resistant to the antibiotics microbes that are susceptible to the antibiotics chickens that are resistant to infection
I gave my students this multiple choice question: Some antibiotics used to treat infections in humans are also used to treat chickens, but some groups oppose this practice. The overuse of the antibiotics will most likely influence the natural selection of which type of organisms?

Only one answer is correct among these 4 choices:
- chickens that naturally make the antibiotics
- microbes that are resistant to the antibiotics
- microbes that are susceptible to the antibiotics
- chickens that are resistant to infection

Could you tell me which one is correct?

microbes that are resistant to the antibiotics