Which of the Following Statements About Diffusion Is True

Which of the following statements about diffusion is true?

A) Gas exchange in tissues in not an example of diffusion
B) Diffusion is the net movement of molecules or atoms from a region of higher concentration to a region of lower concentration
C) Osmosis is not an example of diffusion
D) Diffusion is the net movement of molecules or atoms from a region of lower concentration to a region of higher concentration