Answer:
C. small aircraft pilots
Step-by-step explanation:
Generally, the road users can be classified as pedestrians, cyclists and motorists. Pedestrians are people walking on the road, cyclists are riders of bicycle, motorcycle or tricycle, and motorists are drivers of vans, cars, vehicles etc. These three classes of users make use of road very often.
An aircraft do not make use of roads because it flies, making use of air travel as required. This make option C the appropriate answer to the question.