The biggest design innovation that SpaceX has pioneered is, of course, the fact that Dragon 2 is partially reusable, potentially resulting in a significant cost reduction. The first stage of the spacecraft is capable of re-entering the atmosphere and landing vertically after separating from the second stage.
The correct answer to the question is letter D. Economic Regions
The sun appears to cross the plane of Earth's equator
when it reaches either one of the "equinox" points in the sky.
At those times, the lengths of day and night are nominally equal
everywhere (except at the poles), and the occasions are marked
as the beginning of Spring and Autumn.
