Situation: I am sitting on a chair and there is a bookshelf behind me.
Alternative situations: Just took some books from a shelf behind me and am reading one them right now, while there is a whiteboard on my right. I am sitting in the chair having a conversation with a friend and to our left is a door. I am sitting in a chair looking at the red and black office chair. I am sitting on the blue chair in the bottom right corner of the room drinking water on a water bottle.
Question: What color is the backpack on my left?