An equinox occurs when the sun is directly above the equator, leading to nearly equal day and night durations worldwide.
A. Days are longer than nights – Incorrect. Happens during summer solstice.
B. Days and nights are equal – Correct. This is the definition of equinox.
C. Days are shorter than nights – Incorrect. Happens during winter solstice.
D. None of these – Incorrect. Option B is the accurate definition.