Which of the following best explains the importance of microorganisms in maintaining the quality of groundwater used for drinking in the United States?

• A. Microorganisms increase the salinity of groundwater, making it safer to drink.
• B. Microorganisms prevent the infiltration of water into aquifers.
• C. Microorganisms directly supply essential minerals to groundwater.
• D. Microorganisms help degrade organic pollutants, thereby purifying groundwater.

Answer: (D)

Verified step by step guidance

1. Understand the role of microorganisms in natural water systems, particularly groundwater, which is a major source of drinking water.
2. Recognize that microorganisms can metabolize and break down organic pollutants present in groundwater, such as pesticides, industrial chemicals, and waste products.
3. Know that this biodegradation process helps to reduce harmful contaminants, improving the overall quality and safety of the groundwater for human consumption.
4. Evaluate the incorrect options: microorganisms do not increase salinity, prevent water infiltration, or directly supply minerals to groundwater in a way that affects drinking water quality.
5. Conclude that the key importance of microorganisms in groundwater quality is their ability to degrade organic pollutants, thus naturally purifying the water.