Which of the following is a common groundwater contaminant?
a) ozone
b) nuclear waste
c) carbon monoxide
d) fertilizers

D) Fertilizers

Explanation:

Groundwater pollution occurs when toxic artificial products (generally man made) are released into the soil and descend into the groundwater, making it unsafe and not apt for human (or any living being) consumption.

Among the polluting products are gasoline, waste from residential septic tanks or wells that were abandoned or built incorrectly. However, the most common contaminants are pesticides and fertilizers used in agriculture, which seep into the groundwater through irrigation systems.