What Is the Least Expensive and Most Effective Way to Protect

Multiple Choice

What is the least expensive and most effective way to protect groundwater?

A) Pump it to the surface, clean it, and return it to the aquifer.
B) Inject microorganisms to clean up contamination.
C) Pump nanoparticles of inorganic compounds to remove pollutants.
D) Use methods to prevent contamination.
E) Use bottled water as a substitute.