A Nurse Noted That of 18 Children in a Daycare

A nurse noted that of 18 children in a daycare center room,5 became ill.Which of the following best describes a host factor that may be associated with this illness and who became ill?

A) Some of the children were from very low socioeconomic families.
B) Some of the children inhaled car exhaust while playing outside.
C) The bacterial cause of the illness was easily removed by hand washing.
D) The daycare center room was much warmer on three sides in comparison to the side with the floor to ceiling windows.