What is the answer for y%x where 'x' is zero or a factor of 'y'?

Question

For this same question, the JS challenges accepts either 1 or 0

Answer 1

many of the questions are incorrect in the challenges. For (50=x) , x++ it has 4 spaces in the blank

Answer 2

If x is a factor of y, I believe it's 0. But for x = 0, I don't think the answer is one of the two...