Answer:
the equator
Step-by-step explanation:
Equinox means equal nights. March 21st marks the vernal equinox- a day when the sun passes directly over the equator. On this day, sunlight falls equally in both the hemispheres. This means there would equal day and night in all the parts of the world.
Thus, correct answer is equator is directly beneath the Sun on March 21st equinox on Earth.