What Method of Movement Requires the Expenditure of ATP Molecules

Question

What method of movement requires the expenditure of ATP molecules?  
A) Simple diffusion
B) Facilitated diffusion
C) Osmosis
D) Active transport
E) Bulk flow

Accepted Answer

Active transport requires the expenditure of ATP molecules to move molecules or ions against their concentration gradient. Simple diffusion, facilitated diffusion, osmosis, and bulk flow do not require the expenditure of ATP molecules.