Transborder Environmental Impacts Can Take Place When One Country's Pollution

Transborder environmental impacts can take place when one country's pollution spills over into a second country in all of the following situations except

A) when an upstream user pollutes a shared watershed.
B) when industrial production in one country creates acid rain in another country.
C) when heavy traffic between two or more countries creates semi-global warming.
D) the production of exported products degrades the local environment.