c. sodium-potassium pump
a. osmosis – this is a type at of passive transport. It is diffusion specific to water molecules.
b. diffusion – this is also a type of passive transport. Molecules move from a high concentration to a low concentration down a concentration gradient. This is passive transport and does not require energy.
c. A sodium-potassium pump is a type of active transport, it uses energy to move ions across the membrane. They cannot pass through the membrane because they are charged.
d, facilitated diffusion is a type of passive transport through which substances are transported through proteins in the plasma membrane.