Final answer:
Rail transport is the largest in terms of ton miles moved in the U.S., surpassing road, air, and water transportation due to its efficiency and capacity for moving goods over long distances. The correct answer is option: a) Rail.
Step-by-step explanation:
In the United States, the transportation mode that is the largest in terms of ton miles moved is rail logistics. Rail is highly efficient for moving large quantities of goods over long distances. When comparing different modes of transportation like rail, air, road, and water, it is clear that each has a unique efficiency and cost associated with it.
According to energy measures, while trucks (road) have a better energy usage in kWh/km than ships (water), ships are approximately four times more efficient per ton, thanks to their capacity to carry significantly more cargo.
However, rail still surpasses road, air, and water transport in the total ton miles moved, due to its combination of efficiency and capacity for moving goods across the continental U.S. The efficiency of rail is seen in its ability to move heavy loads using less energy per ton when compared to other modes of transport, making it the dominant choice for freight transportation in the country.