I belive the answer is all of the above
Physical structures..........
It's around equal but girls.
If later is was 100 million years ago, later b would be 200 million years ago (because it is 100millions years prior to a). And therefore layer c must b 300 million years ago.
Answer:
The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. The basic function of the cell membrane is to protect the cell from its surroundings. It consists of the phospholipid bilayer with embedded proteins.
