Endocytosis and exocytosis are forms of active transport. What is active transport?(1 point)

A. the movement of molecules up a concentration gradient from low to high, using energy

B. the movement of molecules down a concentration gradient from high to low, using energy

C. the movement of molecules up a concentration gradient from low to high, using no energy

D. the movement of molecules down a concentration gradient from high to low, using no energy