What causes the production of oxides of nitrogen?

The production of oxides of nitrogen is primarily associated with high-temperature conditions, such as those found in car engines during combustion. At elevated temperatures, nitrogen from the atmosphere can react with oxygen to form nitrogen oxides (NOx), a process known as thermal fixation. This reaction typically occurs at temperatures above 1200 degrees Celsius, which is common in gasoline and diesel engines.

In high-temperature environments, the energy is sufficient to break the strong bonds between nitrogen molecules, allowing them to react with oxygen and form various nitrogen oxides, including nitric oxide (NO) and nitrogen dioxide (NO2). This chemical reaction is a significant contributor to air pollution and is a concern in vehicle emissions.

While other options such as low-temperature combustion or natural processes like lightning can also lead to the formation of oxides of nitrogen, they do not occur at the same significant quantities as seen in high-temperature combustion processes in engines. Industrial chemical reactions may produce nitrogen oxides, but the most prevalent source is still the high-temperature combustion in vehicle engines, which is why that choice stands out as the most accurate answer.