Answer:
here's the answer to your question hope it helps you
Explanation:
a. more subtle
You never put any of the answers
Vaccination has been one of the most successful developments of medical science because for centuries it has been proven effective in diminishing the number of people at risk on certain kinds of diseases. How does vaccination help? Vaccines are contained weakened organisms that are injected to the body. This then boosts the immune system as they release a certain type of cells to combat with the foreign organisms. When the person is exposed to the same organisms again, he/she will develop immunity.
They have an effect because the bigger the school the more activities you can do because you have more people.
