Answer:
Integral membrane protein that forms channel or protein.
Step-by-step explanation:
Facilitated diffusion may be defined as the movement of the particles along the concentration gradient of the cell. This type of diffusion is passive process and does not require ATP.
Facilitated diffusion requires special channels or proteins that are made of the integral membrane proteins. These proteins helps in the transport of molecules from the higher region of the concentration to the lower region of concentration.
Thus, the correct answer is integral membrane channel or pores of protein.