Which of the following is most likely a consequence of high motor vehicle traffic?

High motor vehicle traffic is a significant contributor to air pollution, primarily through the emissions of nitrogen oxides (NOx) and volatile organic compounds (VOCs). When these pollutants are released into the atmosphere, they can react with sunlight, leading to the formation of photochemical smog, particularly in urban areas with heavy traffic. This smog is characterized by a brownish haze and is particularly prevalent in warm, sunny conditions, impacting air quality and public health.

In contrast, increased biodiversity and improved public transportation are generally not associated with high levels of vehicle traffic, as urbanization and road infrastructure can fragment habitats and displace wildlife. Reduced air pollution is contradictory to the effects of heavy traffic, which typically exacerbates air quality issues. Hence, the consequence of photochemical smog arising from high motor vehicle traffic is the most accurate representation of this environmental issue.