Which of these describes diffusion?

a
The active transport of particles into a cell
b
The net movement of any type of molecule from a region of lower concentration to a region of higher concentration
c
The active transport of particles out of a cell
d
The net movement of any type of molecule from a region of higher concentration to a region of lower concentration

d

The net movement of any type of molecule from a region of higher concentration to a region of lower concentration

The correct answer is d. Diffusion is the net movement of any type of molecule from a region of higher concentration to a region of lower concentration.