According to a study of American Year Five students, ______ spent more than 50 times as many minutes a day reading for pleasure as less fluent readers.

A．For protection against other animals.
B．For protection against other dogs.
C．Just for fun.
D．For the purpose of guarding the house.

A．Customer and assistant.
B．Father and daughter.
C．Dentist and patient.
D．Teacher and student.