Answer :
they say carrier protein can transport ions and moecules passtively or using secondary active transport
Answer;
C) Carrier proteins
Carrier proteins are responsible for the transport of substances down a concentration gradient during facilitated diffusion.
Explanation;
-Facilitated diffusion is one of the physiological processes which is a form of facilitated transport that involves passive movement of molecules along their concentration gradient, guided by the presence of other molecules known as carrier proteins.
-These carrier proteins enhance diffusion of molecules across the cell membrane. The proteins are embedded in the membrane of the cells and covers the entire membrane. This feature is crucial since the carrier must carry molecules in and out of the cell.