What is the only effective way to protect groundwater? 

A)  treat all water from underground sources 
B)  use monitoring wells 
C)  prevent contamination 
D)  cover all wells carefully

The only effective way to protect groundwater is to prevent contamination. Once groundwater is contaminated, it can be difficult and costly to clean up, so it is important to prevent contaminants from entering the groundwater in the first place. This can be done through measures such as proper disposal of hazardous materials, avoiding the use of harmful chemicals near groundwater sources, and maintaining septic systems properly. Treating water from underground sources and monitoring wells are important steps in protecting groundwater, but they are not sufficient on their own. Covering wells carefully can help to prevent physical contaminants from entering groundwater, but it does not address other sources of contamination.