If Approximately One in Every Five People in North America

If approximately one in every five people in North America suffers with a diagnosable mental illness at any given time,Violet wonders why more people in ages past did not have problems with mental illness.She researches the question and learns that

A) mental illness rarely afflicted famous historical people,so it was rarely noted in the history books.
B) mental illness was very rarely a problem until the industrial age,and scientists suspect that pollution has contributed to the rising statistics.
C) mental illness rarely afflicted famous historical people and it was very rarely a problem until the industrial age.
D) many historical people did in fact suffer with mental illness during their lifetimes.