Answer the following question given this paragraph: Many viral diseases can be prevented by giving people vaccines (see Figure below ). A vaccine is a substance that contains pathogens such as viruses. The pathogens have been changed in some way so they no longer cause disease. However, they can still provoke a response from the host's immune system. This results in immunity, or the ability to resist the pathogen. Vaccines have been produced for the viruses that cause measles, chicken pox, mumps, polio, and several other diseases. Q: Many viral diseases can be prevented by giving people what? Choices: - Lactose - pesticides - cancers - vaccines A:
The answer to this question is:
vaccines