In active transport, a. vesicle inside the cell fuses with the plasma membrane and releases its contents outside the cell. b. the plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. c. molecules move across the plasma membrane by crossing the lipid bilayer directly, rather than by using a transport protein. d. molecules move across the plasma membrane against their concentration gradient. e. no energy input is required from the cell.