Vaccines help prevent illnesses. Vaccines keep the environment cleaner. Vaccines help cure people who are sick. Vaccines kill bacteria that cause infections.
I gave my students this multiple choice question: New vaccines for diseases are being developed all the time. How do vaccines most likely help people?

Only one answer is correct among these 4 choices:
- Vaccines help prevent illnesses.
- Vaccines keep the environment cleaner.
- Vaccines help cure people who are sick.
- Vaccines kill bacteria that cause infections.

Could you tell me which one is correct?

Vaccines help prevent illnesses.