The correct option is C Speed
Option C is the correct answer. The author is vehement about the speed that an automobile offers one, which is necessary at times. Without devaluing the convenience and the cost effectiveness of an automobile, the passage tries to establish the advantage of automobile travel instead of public transport in North America based on the fact that the former is faster than the latter, and helps one to get to their destinations quicker, without having to deal with unnecessary disturbance. There has been no reference the environmental impact that automobiles have. Thus, option A,B and D are incorrect.