ANSWER
Option D
Step-by-step explanation
We want to find the equation that could be a possible function of x of the given graph.
To solve this, we have to apply the knowledge of the roots of an equation/function.
We know that for an equation:
The roots of the equation are a and b.
For a graph, the roots of the graph (for a quadratic graph) are the x values of the two points where the graph touches the x axis.
From the given graphs, we see that the two roots of the graph lie on the positive x axis. This means that the roots of the function must be positive.
Therefore, from the function above, a and b must be positive values.
The only options that provide us with this possibility is option D where a and b are 3 and 7 respectively.
Therefore, the correct answer is Option D.