answer: #Person2# introduces the purposes of using horses mentioned in the TV program he watched to #Person1#.
documents: #Person1#: What were you doing when I called you last night?
  #Person2#: I was watching a TV program, it was about how people use horses for various purposes.
  #Person1#: Oh, I love horses. I think they are very useful.
  #Person2#: Yeah, people use them for sports and entertainment, and horse races take place in many countries.
  #Person1#: What else can horses help people do?
  #Person2#: Yes, horses are still used in some countries to do farm work.
  #Person1#: Really? What a hard job. Well, let's go horse riding together this weekend.
  #Person2#: I'd love to, but John has invited me to his wedding.