Recall that the x-intercepts of a graph that represents a polynomial give us the real roots of the polynomial.
Now, the first two graphs are parabolas, therefore they represent a second-degree polynomial, the third graph has 4 x-intercepts, therefore it represents a polynomial of degree at least 4.
The last graph crosses the x-axis 3 times, therefore, it could represent a cubic equation.
Answer: Last graph.
