Explain why the graph of quadratic could not contain both a mimum vertex and a maximum vertex at the same time.

The graph of any quadratic is a parabola. Parabolas are shapes that look like a bowl or dish of some kind. The curve only changes direction one time. This is important as this point where the change occurs is the vertex. Parabolas have one vertex only. Either the vertex is the highest point or the lowest point. It's impossible to have both at the same time. 

Ithink the answer is d.