What describes an efficient and rapid transport system for automobiles across urban areas?

The correct answer is freeway, as it specifically refers to a type of transport system designed for high-speed vehicular traffic. Freeways are characterized by features such as multiple lanes, no traffic signals or intersections, limited access points, and designs that minimize stop-and-go traffic. This makes them highly efficient for moving a large volume of vehicles quickly across cities and urban areas, as they allow for uninterrupted flow of traffic over long distances.

In contrast, highways can refer to any major road but may have intersections and traffic lights, which can slow down transit. Streets typically serve local traffic with more frequent stops, and main roads often carry medium levels of traffic, potentially complicating movement due to lesser design specifications compared to freeways. Thus, freeways are specifically engineered to facilitate quick and efficient transportation, making them the ideal choice for this question.