The intensity of sunlight received at a location on Earth is greatest when the sunlight strikes the surface at a perpendicular angle (90°). This is because sunlight concentrated over a smaller surface area results in higher intensity.
Among the angles provided:
- 90° at the equator represents sunlight striking directly overhead.
- 75° in the tropics is still a fairly high angle.
- 50° in North America and 25° in the Arctic Circle represent more oblique angles, resulting in lower intensity of sunlight.
Therefore, the angle where the intensity of sunlight received will be the greatest is 90° at the equator.