What is the correct description of the relationship between osmosis and diffusion?
a. diffusion is a type of osmosis that occurs across a cell membrane.
b. osmosis is a type of diffusion that occurs across a cell membrane.
c. osmosis is a type of diffusion that requires energy on the part of the cell, whereas diffusion happens freely.
d. osmosis is not directly related to diffusion. osmosis involves the movement of liquids. diffusion involves movement of gases.