Answer:
Ivy's definition matches the comment that starts with "Sorry, this is incorrect. An ellipse..." because she didn't specify that the points that belong to the circle must be the same distance away from the center point. According to Ivy's definition, any curved and closed shape would be a circle but that's not true. For example, like the teacher said, an ellipse would match her circle definition but an ellipse is not a circle, it's more like an oval-ish shape. Ethan's definition is correct. Ebuka's definition matches the comment that starts with "Your definition is close..." because he/she didn't say that the shape must be closed. According to Ebuka's definition, an incomplete curve could count as a circle but that's not true, for example, as the teacher said, a semicircle is not a circle.
