SAT Question f67e4efc: Area and Volume answer and explanation with Desmos solution

Choice A is correct. The volume of a right circular cylinder with a radius of $r$ is the product of the area of the base, $\pi r^2$, and the height, $h$. The volume of the right circular cylinder described is $45\pi$ and its height is $5$. If the radius is $r$, it follows that $45\pi =\pi r^2\times 5$. Dividing both sides of this equation by $5\pi$ yields $9=r^2$. Taking the square root of both sides yields $r=3$ or $r=-3$. Since $r$ represents the radius, the value must be positive. Therefore, the radius is $3$.