How do resistant bacteria form?

• A. People don't kill all the bacteria so the strongest remain and reproduce
• B. They are created by a special lab
• C. They come from eating spoiled food
• D. They vanish when you drink water

Answer: (A)

Antibiotic resistance forms through natural selection: when an antibiotic is used, it tends to kill most susceptible bacteria, but some have or acquire genetic traits that let them survive. Those survivors reproduce and pass the resistance on to their offspring, and sometimes share resistance genes with other bacteria. Under ongoing drug exposure, the resistant group becomes more common. So the idea that not all bacteria are killed, and the survivors multiply, best explains how resistance develops. It isn’t created in a lab, doesn’t come from spoiled food, and isn’t eliminated by drinking water.