Read the paragraph from "The Workers of Ellis Island."

Both female and male nurses were required to live on the island and were assigned separate quarters. According to PHS regulations, all nurses visiting New York and New Jersey on their off-duty hours were required to return to Ellis Island no later than the 12:00 a. m. staff boat.

Which statement best describes the central idea of the paragraph?

a)and male nurses lived in separate quarters on Ellis Island.
b)The Public Health Service (PHS) regulated the actions of the Ellis Island nurses.
C)Ellis Island nurses visited New York and New Jersey on their off-duty hours.
D)Ellis Island nurses had to return to the island on the 12:00 a. m. staff boat.