The full question (and there had been previous just like it) was Sides___ and Corners ______
The polygons all had the sides and corners being equal, so her correct answer is most likely zero.
Or infinity, because a circle can be considered to have an infinite number of infinitesimal sides and corners. You’re probably right, though. Infinity is not a concept expected to be in the wheelhouse of 1st graders, but zero is.