The question asks us to identify the dominant source of pollution regarding the emission of oxides of nitrogen (NOX) in urban areas. Let's examine the given options to find the most accurate source of NOX pollution:

1. Road Transport: Road transport is a major source of NOX emissions due to the combustion of fossil fuels in vehicle engines. The internal combustion process in cars, trucks, and buses contributes significantly to the production of NOX, especially in urban environments where vehicle density is high.
2. Commercial Sector: This sector includes various commercial activities, which might contribute to pollution through energy use but is a relatively minor contributor to NOX emissions compared to transportation.
3. Energy Use in Industry: Industries contribute to NOX emissions, especially those involving combustion processes. However, in urban areas, the concentration of such industries might be less impactful compared to road transport vehicles.
4. Power Plants: Power plants, especially those running on fossil fuels, contribute to NOX emissions. However, they are typically located away from densely populated urban centers, reducing their relative impact compared to direct sources such as vehicles within urban areas.

By evaluating the above options, we can conclude that road transport is the most significant source of NOX pollution in urban areas. This is primarily due to the high number of vehicles operating in close quarters, leading to concentrated emissions and lower dispersion.

This analysis aligns with the current understanding that vehicular emissions are a primary concern in managing urban air quality. Therefore, the correct answer is road transport.