Which of the Following Correctly Describes How Bottled Water and Water

Which of the following correctly describes how bottled water and water in public drinking systems are purified?

A) They are usually both purified using chlorine.
B) They are usually both purified using ozone.
C) Bottled water is usually purified using chlorine, but public drinking systems are usually purified using ozone.
D) Bottled water is usually purified using ozone, but public drinking systems are usually purified using chlorine.