Which of the Following Was Not One of the Causes

Multiple Choice

Which of the following was not one of the causes of nationwide epidemics in the United States during the antebellum period?

A) Municipal health boards had little power and therefore could do nothing to stop diseases from spreading.
B) People distrusted physicians and their advice.
C) Doctors did not understand the causes of disease.
D) The transportation revolution enabled epidemics to spread.
E) The widespread use of laughing gas by young people seriously suppressed their immune systems.