__is the distance traveled during a specific unit of time.
21 pts

i think the answer is a, hope this is right, that would be my best guess.

as we know our atmosphere or air have different levels. every level has other gasses, and every gas has another permeability. when the light comes from lower permeability to higher permeability, it changes its direction. so that means that when the light comes from the moon to the earth, it changes it's direction many more times. it basically means that the shape of the light part of the moon is changed on the earth.

hope this ! this is not copied! search it up, it's free of plagiarism!

b. a lightning bug, plug of grass, and a worm