I believe the answer is: positive externality
Positive externality refers to The benefit that enjoyed by a third party when the first and second party are conducting a transaction.
When you receive a vaccines, you prevent yourself from becoming a host that could contaminate other people from getting the virus. In the example above, you and your children are the first and second party. And other children are the third party.
disease is the correct answer
D is the answer passing laws that protected child workers
Galen's area of expertise were in pharmacology, surgery and anatomy. He was also known by the name of "father of experimental physiology". He was not only a biologist but also a physician. He was born in 129 AD and died on 219 AD. He was very famous for making the first experimental medicine.
