Final answer:
An ellipse is drawn around two special points called foci (option D). These points are unique in that the sum of the distances from any point on the ellipse to the two foci is constant, a fundamental property of an ellipse's geometry.
Step-by-step explanation:
An ellipse is drawn around two special points called foci. The correct answer to the question is D. foci. These points are significant because they have a unique geometrical property that describes an ellipse: for any point on the ellipse, the sum of the distances from that point to the two foci is constant.
To illustrate, consider Figure 3.4, where an ellipse is constructed using two tacks and a string. Each tack represents one of the foci; one could be the Sun in the case of an orbital ellipse. With the string stretched tight, a pencil traces out an ellipse, keeping the sum of the distances from any point on the curve to the two tacks always the same.
In contrast to the terminology related to elliptical orbits in space, aphelion (labeled point B) and perihelion (labeled point A) refer to the farthest and closest points of a planet's orbit around the Sun, respectively, but not to the foci of the ellipse. Thus, choices B and C can be eliminated. Additionally, an axis (E) runs through the center of the ellipse and along its widest part, but it is not a focus. Hence, the only accurate term for the two special points around which an ellipse is drawn is 'foci.'