Answer:
Temperatures in the atmosphere decrease with height at an average rate of 6.5°C/km. Because the troposphere experiences its warmest temperatures closer to Earth's surface, there is great vertical movement of heat and water vapour, causing turbulence.
Nitrogen oxides are produced by the combustion engines in vehicles. Their effect on the environment includes both acid rain and smog.
C. They must be certified by the AVMA.
I would say the answer is C. D isn't right because mammoths didn't exist when dinosaurs did. And cyanobacteria were the first living organisms on earth.