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.
Answer:
its either Boston, New York or Philadelphia
Alfred Thayer Mahan was the one who took the position that the United States should establish naval bases outside of the country. Alfred was named "the most important American strategist of the nineteenth century", and was known for being a naval officer for most of his life.
