answer: Sue advises Jack to advertise his book himself. Jack thinks he'll market it.
documents: #Person1#: Hi, Jack. It's several months since I last saw you.
  #Person2#: Hi, Sue. I've been busy with my book.
  #Person1#: Haven't you finished it yet?
  #Person2#: I will have in a few days.
  #Person1#: Are you going to advertise it yourself?
  #Person2#: Hmm...Some friends suggested I should, but I'm still in 2 minds about it.
  #Person1#: If I were you, I would.
  #Person2#: Thank you for your advice. I think I'll market it.