Final answer:
The equator receives roughly the same amount of solar radiation all year because it is situated in the middle of Earth's hemispheres and does not experience the significant shifts in sunlight that occur during the solstices at higher latitudes. The correct answer is option (a).
Step-by-step explanation:
The equator receives a roughly equal amount of solar radiation throughout the year due to its position at the center of Earth's hemispheres. At the equinoxes, which occur around March 21 and September 21, the Sun shines directly over the equator, providing approximately 12 hours of daylight and 12 hours of darkness everywhere on Earth. The equator doesn't experience the extreme shifts in sunlight that higher latitudes do during the solstices; for example, during the summer solstice, the Sun shines most directly upon the Northern Hemisphere, specifically at the Tropic of Cancer (23° N latitude).
On the opposite side, during the winter solstice, the Sun shines most directly upon the Southern Hemisphere. Therefore, the amount of solar radiation received at the equator remains relatively the same all year, without the marked changes seen at higher latitudes.