Explanation:
Third Option is absolutely correct.
Protects brain and spinal cord from trauma, as well as supplies nutrients to nervous system tissue. It also removes waste from cerebral metabolism.
The erosion or disintegration of rocks, building materials, etc., caused by chemical reactions (chiefly with water and substances dissolved in it) rather than by mechanical processes
It’s the first choice because the C at the end does not pair with anything, it was an extra pair that was made
I believe the correct answer would be B. Semipermeable means that it allows certain substances to pass through, and certain other ones to not pass through. So given all of your options, I would say that B makes the most sense. Hope this helped!
-TTL