Type of transport protein alternates between two shapes, transporting the solute across the membrane through shape changes.

The correct answer is- carrier protein

Explanation:

Carrier proteins are involved in the transport of a substance across the membrane. They bind to substance specifically and are involved in both facilitated diffusion and active transport.

They usually change their conformation or shape to transport the molecule across the cell. When they bind to a molecule they change their shape and then they get into their normal shape when the molecule gets transported across the membrane.

The rate of diffusion by using carrier protein is higher than simple diffusion. So the correct answer is carrier protein.