A is sitting at a table seat on a train, on the aisle seat and the window seat is empty. B gets on the train and asks to sit in the empty seat next to A. A says sorry, I'm holding this for my friend (C) who is just getting on now.
B says I'm here and I would like to sit down please (may not be exact words).
A gets up to find another seat. C is not far behind her as she has just got on the train and says "what a bitch. I was literally behind you" about A.
Who is unreasonable?