Question

the process of molecules moving across a membrane from high to low concentration using specific membrane proteins, but without energy, is called: active transport. active diffusion. facilitated diffusion. simple diffusion.

Explanation:

The process described involves molecules moving down their concentration gradient (high to low) without energy, using specific membrane proteins. Active transport requires energy, active diffusion is not a standard term, and simple diffusion does not use membrane proteins. Facilitated diffusion matches all the criteria.

Answer:

C. facilitated diffusion.