According to the author, by interacting with people who study liberal-arts, engineering students can______.

A．The ideal retirement age for an experienced football referee is 35.
B．Age should not be the chief consideration in choosing a football referee.
C．A football referee should be as young and energetic as possible.
D．An experienced football referee can do well even when in poor physical condition.

A．4) most probably refers to______.A. the researchers involved in the experimentB. the inspectors of the football tournamentC. the referees of the football tournamentD. the observers at the site of the experiment