The correct answer is E) positive externality.
The economic concept that is applied in this statement is "positive externality."
The statement is: In other words, you are not only protecting your own child by getting her vaccinated, but you are also protecting other children—and adults too.
When we are talking about economics, the term "positive externality" is applied when some else is receiving a benefit from a transaction between two parties. In this case of the vaccine, you benefit your children and because they will be protected against infections, they are not going to transmit the infection to other children, That would be the "positive externality."
