The solar eclipse achieves totality only in limited geographical regions because

• A. The size of the shadow of the moon on the earth is small as compared to the cross section of the earth
• B. The earth is not smooth flat surface, but has elevations and depressions
• C. The trajectories of the earth around the sun and the moon around the earth are not perfect circles
• D. Sun rays can reach most of the peripheral regions of shadow of the moon due to atmospheric refraction