Environmental engineering can be defined as the area where impact of human activities on environment takes place.
Human activities as mining, deforestation, building dams has huge impact on the environment.
This is studied under environmental engineering. This subject also allows to find solution for the problems associated with the impact of human activities on environment.
A. Internal. Most cars use that type of set up because it's more efficient, you can find more about it on this website, https://auto.howstuffworks.com/did-cars-ever-have-external-combustion-engines.htm
