Final answer:
A) Air transportation is the most expensive mode of transportation due to the large distances involved and the high energy expenditure.
Step-by-step explanation:
The most expensive mode of transportation is Air. According to the given information, air travel requires a substantial amount of total energy expenditure because the distances involved are often quite large.
Additionally, air freight is stated to be 100 times more energetically costly than shipping by sea. Therefore, air transportation is the most expensive option.