It's purpose is to break down energy from carbohydrates and other organic molecules stored during photosynthesis
No they don't
For example humans. Technically humans are place below a wild predators such as sharks in trophic levels.
But the fact is we can eat sharks. So , organisms don't always stay in the same level
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