I did very well on these sorts of questions in grade school. One reason was, when the question was ambiguous, I tried to think like the teacher.
I don’t know this 1st grade teacher, but if I had to guess, I’d say s/he would be expecting the answer “1 side”. If it were a smart aleck 8th grade math teacher, I’d go for “2 sides”. If it were a pedantic, blockhead 11th grade teacher, I’d go for “no sides”.
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.