Answer:
<em>The</em><em>re</em><em> is</em><em> </em><em>ac</em><em>tually</em><em> </em><em>diff</em><em>erent</em><em> </em><em>w</em><em>ays</em><em> to</em><em> </em><em>ex</em><em>plain</em><em> </em><em>it</em>
Explanation:
<em>b</em><em>ut</em><em> </em><em>one</em><em> </em><em>of</em><em> </em><em>the</em><em> </em><em>m</em><em>ost</em><em> important</em><em> </em><em>rea</em><em>sons</em><em> </em><em>is</em><em> </em><em>that</em><em>,</em><em> </em><em>A mental disorder, also called a mental illness</em><em> </em><em>or</em><em> psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may be persistent, relapsing and remitting, or occur as a single episode. Many disorders have been described, with signs and symptoms that vary widely between specific disorders. Such disorders may be diagnosed by a mental health professional.</em>
Factories, smoking, cars, littering
I think the answer is drugs but i'm not so sure