SAT Question 9654add7: Nonlinear Functions answer and explanation with Desmos solution

Choice C is correct. By definition, the $y$-value when a function intersects the $x$-axis is $0$. It's given that the graph of the function intersects the $x$-axis at $0$ and $a$, that $x$ is the unit price, in dollars, of a product, and that $f(x)$, where $y=f(x)$, is the revenue, in dollars, that a company receives from the sales of the product. Since the value of $a$ occurs when $y=0$, $a$ is the unit price, in dollars, of the product that will result in a revenue of $$0$.