This method of treating water kills microbes and removes other contaminates such as heavy metals.
a. chlorination.
b. distillation.
c. boiling.

I believe the answer to your question will be B).

The question may be incomplete (there are not the possible answers), but according to the scenario, kaley and her coworkers could be in a humanitarian organization like red cross (in the us or in other countries). it's an organization which organizes health and safety services, disaster services, and blood donations.