What occurs during one half-life?
a. half of a daughter isotope undergoes radioactive decay to form a parent isotope.
b. half of a parent isotope undergoes radioactive decay to form a daughter isotope.
c. all of a daughter isotope undergoes radioactive decay to form a parent isotope.
d. all of a parent isotope undergoes radioactive decay to form a daughter isotope.

 Actually its the parent isotope that undergoes radioactive decay.

So option A and C is not correct.

And in one half life;

what happens is half of the parent isotope decays to form daughter isotopes.

Hence the correct option is B:

B. Half of a parent isotope undergoes radioactive decay to form a daughter isotope.

one negative thing it that it can kill water animals. another negative thing is it can cause the destruction of ecosystem. one way water pollution can be reduced is to conserve energy.