Which evidence would BEST support the claim that using synthetic fertilizer can be harmful to the environment?

Question

A. 

an increase in the number and kinds of microorganisms found in a farm field after the application of synthetic fertilizer to the soil

B. 

an increase in certain nutrients and algae growth in a lake near a farm field after the application of synthetic fertilizer to the soil

C. 

an increase in the number and size of vegetables produced in a farm field after the application of synthetic fertilizer to the soil

D. 

an increase in the number of weeds and a decrease in the number of pest insects in a farm field after the application of synthetic fertilizer to the soil

Answer 1

The best evidence that supports the claim that using synthetic fertilizer can be harmful to the environment is:

B. an increase in certain nutrients and algae growth in a lake near a farm field after the application of synthetic fertilizer to the soil.

This option indicates a potential negative environmental impact, specifically eutrophication, which is the process where excess nutrients (often from fertilizers) runoff into water bodies, leading to excessive algae growth. This process can deplete oxygen in the water and harm aquatic ecosystems, thus providing direct evidence of harm caused by synthetic fertilizers.