听下面一段独白，回答以下小题。
【小题1】Who is the speaker talking to?

A．Office clerks.

B．Medical researchers.

C．Students.

【小题2】Where was the research carried out?

A．In Africa.

B．In the U.S.

C．In the U.K.

【小题3】How many people watched TV for more than four hours in the study?

A．About 1,200.

B．About 2,400.

C．About 3,600.

【小题4】What advice does the speaker give in the end?

A．Getting regular medical check-ups.

B．Taking part in the research.

C．Taking exercise.