The graph of y = x(x + 1)(x – 1)(x – 3) is shown. On a coordinate plane, a curved line shows 2 minimum values at (negative 0.6, negative 1.2) and (2.3, negative 7), and 1 maximum value. Point A is at (negative 1, 0), point B is at (0.5, 1), point C is at (1.5, negative 3), and point D is at (3, 0). Which point is a turning point of the graph? A B C D