The diagram below illustrates substances crossing the selectively permeable membrane of different cells. each example, a-f, shows not only different substances, but also different concentrations. take note of the concentration inside the cell compared to the concentration outside of the cell and the direction of movement of the substance.
figure 3-1

diagram f in figure 3-1 is an example of
a.
diffusion
c.
osmosis
b.
active transport
d.
equilibrium

select the best answer from the choices provided

a
b
c
d