Read the paragraph from "The Workers of Ellis Island." Ellis Island doctors were particularly watching for signs of contagious diseases. Incurable diseases included trachoma and tuberculosis and guaranteed a return trip to where the immigrant came from. Others, like diphtheria, measles and scarlet fever, for example, relegated the immigrant to the contagious disease wards where they were generally treated, cured and released. Sometimes the entire family was held on the Island while a child or responsible adult was being treated.

Which sentence best represents the paragraph's central idea?

Ellis Island doctors were particularly watching for signs of contagious diseases.
Incurable diseases included trachoma and tuberculosis and guaranteed a return trip to where the immigrant came from.
Others, like diphtheria, measles and scarlet fever, for example, relegated immigrants to the contagious disease wards where they were generally treated, cured and released.
Sometimes the entire family was held on the Island while a child or responsible adult was being treated.