The 'Hygiene Hypothesis' Supports Which of the Following Statements

The 'hygiene hypothesis' supports which of the following statements?

A) Children exposed to fewer microbes have fewer allergies and less asthma.
B) Conditions prior to the agricultural revolution were actually more hygienic than today.
C) Environments that are too sterile lower the tolerance of the immune system, leading to more athma and allergies.
D) Immunity to specific diseases requires a sterile birth environment.
E) Contagious diseases spread when people practice poor hygiene.