A potential difference can build up across a cell membrane,but not in a bulk solution inside the cell,because

A) lipids in the cell membrane are hydrophobic and prevent ions from crossing.
B) lipids in the cell membrane capture ions and prevent them from crossing.
C) proteins in the cell membrane capture ions and prevent them from crossing.
D) proteins in the cell membrane are hydrophobic and prevent ions from crossing.
E) there is no way to move ions from one side of a membrane to the other side.