Draw the position - time graph of a body moving with zero velocity.

I drew the graph (parallel to x-axis) and got full marks . And one of my friend drew the graph (coinciding x-axis) but , he got only 0.5 marks out of 2 . When he asked the teacher, she said that the position = 0 is not defined .But in many of the graphs we start from position = 0.So, what is the mistake in my friend's answer? Isn't his answer correct?