Visualizing the Problem

Below you see two circles. The second's diameter is $3$ times the first's.

ETS is trying to get us to fall into the trap that the area of the larger circle is $3$ times that of the smaller circle. As you can see from the image, this is clearly NOT the case. Don't fall for the trap!

Solving the Problem

If we imagine the diameter of the smaller circle $D$ is $2$, then its radius is $1$, and its area below:

$$ area = \pi r^2 = \pi 1^2 = \pi$$

The diameter of circle $C$ would be $6$, its radius would be $3$, and its area is below:

$$area = \pi r^2 = \pi 3^2 = 9 \pi$$

As we can see, circle $C$'s area is $9$ times that of circle $D$. The correct answer is $9$.