answer: #Person1# asks to take a picture of #Person2# and #Person2#'s boy for a book. #Person2# agrees.
documents: #Person1#: Excuse me. May I take a picture of you and your little boy? 
  #Person2#: What's it for? 
  #Person1#: It's for a book. 
  #Person2#: Oh, that's a nice idea. Well, it's fine if you take our picture. 
  #Person1#: Thank you. I appreciate your help.