Which issue is least likely to have been the result of human impact on the nitrogen cycle?

A) Photochemical smog
B) Global warming
C) Acid rain
D) El Niño-Southern Oscillation events
E) Depletion of the ozone layer

Nitrogen Cycle

A biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere, terrestrial, and marine ecosystems.

Human Impact

The effects and consequences of human activities on the environment and its natural processes.

Photochemical Smog

Mixture of several air pollutants that injure plant tissues, irritate eyes, and cause respiratory problems in humans.