What is the Force Driving Simple Diffusion and Energy Source

Question

What is the force driving simple diffusion and energy source for active transport,respectively?
A)the concentration gradient; ADP
B)the concentration gradient; ATP
C)transmembrane pumps; electron transport
D)phosphorylated protein carriers; ATP
E)proton gradient; ADP

Accepted Answer

Simple diffusion is driven by the concentration gradient, while active transport requires energy, typically provided by ATP.