Why can some water get through the cell membrane without a protein channel? A. Because it is fully charged
B. Because it is nonpolar
C. Because it is large
D. Because it is small

Explanation: Water can diffuse through the lipid bilayer even though it's polar because it's a very small molecule. Water can also pass through the cell membrane by osmosis, because of the high osmotic pressure difference between the inside and the outside the cell.