The health officials investigating the recent outbreak of measles said that most cases were present in school aged children. _____ This transmission later continued within the family, as sisters and brothers of infected children caught the illness because there were no visible symptoms during the incubation period.
A) It is not difficult to catch measles at that age.
B) The incubation period is the only time that the illness is spreadable.
C) Children often play together in a rather rough fashion.
D) The high communicability of the disease caused a quick spread in the crowded classroom environment.
E) Parents don't believe it is necessary to isolate their children from those children that are ill.
