Final answer:
The departure of Earth from a perfectly circular orbit is referred to as orbital eccentricity.
Step-by-step explanation:
The correct answer is Option D) Orbital Eccentricity.
The departure of Earth from a perfectly circular orbit is referred to as orbital eccentricity. An ellipse is a type of orbit that has an elongated shape, with the sun (or the central body) not at its center but near one end. The degree of elongation of an elliptical orbit is called its eccentricity, which is calculated by dividing the distance from the center of the ellipse to one of the foci by half of the long axis.