The correct answer is To Kill germs. Explanation & Key Takeaways: • As a halogen, chlorine is a highly efficient disinfectant and is added to public water supplies to kill disease-causing pathogens, such as bacteria, viruses, and protozoans, that commonly grow in water supply reservoirs, on the walls of water mains, and in storage tanks. • In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, and typhoid. • As a strong oxidizing agent, chlorine kills via the oxidation of organic molecules. • Chlorine and its hydrolysed product hypochlorous acid are not charged and therefore easily penetrate the negatively charged surface of pathogens. • It is able to disintegrate the lipids that compose the cell wall and react with intracellular enzymes and proteins, making them nonfunctional, microorganisms then either die or are no longer able to multiply.