Regarding Polio-Having Better Sanitation and Smaller Families Led to

Regarding polio-having better sanitation and smaller families led to

A) less contact with the disease, thus a lack of development of disease immunity.
B) more contact among fewer siblings giving the virus more time to develop stronger among fewer people.
C) greater chances of physical transfer of disease from parent to child.
D) the unlikely transmission of disease from wood in new suburban homes.