Correct Option: C

The name “equinox” is derived from the Latin aequus (equal) and nox (night), because around the equinox, the night and day have approximately equal length. An equinox occurs twice a year (around 20 March and 22 September), when the tilt of the Earth’s axis is inclined neither away from nor towards the Sun, the center of the Sun being in the same plane as the Earth’s equator. The term equinox can also be used in a broader sense, meaning the date when such a passage happens. The equinoxes are the only times when the sub-solar point is on the Equator. This point (the place on the Earth’s surface where the center of the Sun can be observed exactly overhead) crosses the Equator moving northward at the March equinox and crosses the Equator moving southward at the September equinox.