Final answer:
Option A). The sky on Earth appears blue due to scattering of sunlight. The small size of the molecules in Earth's atmosphere causes blue colors of sunlight to scatter more efficiently than other colors, resulting in a blue sky.
Step-by-step explanation:
Because of the dispersal of sunlight, the sky appears blue on Earth. Sunlight is scattered by air molecules as it enters the Earth's atmosphere. The blue hues in sunlight are scattered by the tiny molecules far more effectively than the other colors. As a result, the sky appears blue due to the blue light being dispersed throughout it. Hence, Option A) is the correct answer.