Select the most appropriate ANTONYM of the given word.

CONTAMINATE

cleanse

The correct answer is option 4. cleanse.

"Contaminate" means to make something impure or unsuitable for use by adding harmful or undesirable substances. It implies the introduction of pollutants or harmful agents.

On the other hand, "cleanse" means to remove impurities or pollutants, making something pure or free from contamination. It implies the process of purification or detoxification.

Therefore, "cleanse" is the most appropriate antonym for "contaminate" because it represents the opposite action of removing impurities or pollutants rather than introducing them.