A pond ecosystem remains about the same for many years. Then beginning one year, fertilizer from a new housing development is washed into the pond water. More fertilizer is added every year. As explained by Darwin's theory of natural selection, which of these events is likely to occur?

I. Some populations of the pond will increase in number.
II. Some populations of the pond will decrease in number, possibly to zero.
III. New populations will arrive in the pond.
a
II. only
b
I., II., and III.
c
I. and II.
d
II. and III.