In geography, “scale” refers to
a. the depth of inquiry or the amount of details
b. an instrument used to weigh things
c. how someone perceives or understands something
d. the way that someone looks at something

Air pollution: “combustion results in gases such as nitrogen oxides, nitrogen dioxide and particulates. the main causes of air pollution include transport, domestic combustion and industrial processes. pollutants from these sources can cause problems in the immediate vicinity and a distance away.”

Answerhave flowing water either episodically or during only a portion of the year;

Answer metamorphic rock;