They are said to be “denser” than air. what happens is that light slows down when it passes from the less dense air into the denser glass of water. this slowing down the ray of light also causes the ray of light to change directions. it is the change in the speed of the light that causes refraction.
Collagen supported cells :)
That would be C.
Invasive species are brought to a new area by human activities.
