Concept:March 21 is the equinox, when day and night are almost equal everywhere on Earth.
Explanation:On March 21, the Sun is directly overhead at the Equator.
At this time, the Earth’s axis is neither tilted towards nor away from the Sun.
As a result, the Sun’s rays fall evenly on both hemispheres.
Every place on Earth, including towns in the southern hemisphere, receives about 12 hours of daylight and 12 hours of darkness.
This equality of day and night is a feature of the equinox.
Therefore, towns in the southern hemisphere experience equal length of day and night.
Answer:C. equal length of day and night