Which statement best defines an ellipse and contrasts it with a circle?

• A. The set of all points at a fixed distance from a single center point.
• B. The set of all points for which the sum of the distances to two fixed points is constant.
• C. The set of all points for which the product of the distances to two fixed points is constant.
• D. The set of all points equidistant from two fixed points.

Answer: (B)