The equation of the graph shown plotted in the coordinate plane is y = x + 4. What statement is not true about this graph?
A. Each value of y in an ordered pair that lies on this graph, except 0, is paired with two values of x.
B. The value of x in every ordered pair that lies in this graph is less than the corresponding value of y.
C. The slope between any two points on this graph is constant.
D. The graph of this equation is a function.