Question

which statement describes both a positive impact and a negative impact associated with the effects of nitrogen - based fertilizers?

• they increase polluted runoff and damage drinking water.
• they increase plant growth and damage drinking water.
• they increase denitrifying bacteria and increase plant growth.
• they increase both limiting resources and denitrifying bacteria.

Explanation:

To solve this, we analyze each option:

• First option: "They increase polluted runoff and damage drinking water" – both are negative impacts, so eliminate.
• Second option: "They increase plant growth" (positive, as fertilizers help plants grow) and "damage drinking water" (negative, due to runoff with excess nutrients affecting water quality) – this has both positive and negative.
• Third option: "They increase denitrifying bacteria and increase plant growth" – both are positive or neutral (denitrifying bacteria's impact here is not clearly negative in this context), so eliminate.
• Fourth option: "They increase both limiting resources and denitrifying bacteria" – fertilizers don't increase limiting resources (they provide nutrients, so limiting resources for plants might decrease), and this doesn't show a clear positive - negative pair, so eliminate.

Answer:

B. They increase plant growth and damage drinking water. (Note: Assuming the second option is labeled B; adjust the label based on actual question's option numbering if different, but the content is "They increase plant growth and damage drinking water".)