Increased ozone in the lower atmosphere (near the ground) results primarily from:

• A. Photochemical reactions involving nitrogen oxides (NO_x) and volatile organic compounds (VOCs) in sunlight
• B. Direct emission of ozone from automobile exhaust
• C. Evaporation of ozone from bodies of water
• D. Release of ozone from plants during photosynthesis

Answer: (A)

Verified step by step guidance

1. Understand that ozone (O\_3) near the ground, also called tropospheric ozone, is not typically emitted directly but is formed through chemical reactions.
2. Recognize that photochemical reactions involve sunlight driving chemical changes, particularly involving nitrogen oxides (NO\_x) and volatile organic compounds (VOCs).
3. Recall that nitrogen oxides and VOCs are pollutants emitted from sources like vehicle exhaust and industrial processes, which react in the presence of sunlight to form ozone.
4. Eliminate options that suggest direct emission of ozone or natural release from water or plants, as ozone is highly reactive and does not accumulate from these sources in significant amounts.
5. Conclude that the primary cause of increased ozone near the ground is the photochemical reactions involving NO\_x and VOCs under sunlight.