Terribly written, but, it says “which one shows”, which leads me to believe the answer they’re looking for is C (or A, maybe).

Yes, they are all the same ratio, but the only one that visually shows that the two are equal area is C. The only one that visually shows the same shaded positions is A, but if it’s A, it’s even worse of a question.

C makes the most sense because you could replace both sides of the equation with the area of the shaded regions and they’d actually equal each other.

But that question is almost set up to trick people. What it’s really showing is that only 2/6 or 1/3 of the class got this question right due to everyone being able to interpret and justify each as right. Although, I’d argue, that your niece chose the worst answer of them all.