Sunlight is slowed MOST when traveling through A) water. B) a vacuum. C) the atmosphere. D) None of these, as light always travels at the same speed.

The answer's A

I already did the test and it as right

A

Explanation:

This is because water is the densest medium among the three. This means there are more molecules of the material per unit volume as compared to the other media. Therefore, a ray of sunlight in water bombards with many molecules in its straight path as compared to in atmosphere or vacuum. This slows it down and diffusing it. This is why light does not get to great depths in oceans and some deep lakes leaving these deep layers of water, dark. In vacuum, light can travel the farthest, followed by the atmosphere, then water.