Question

why is air transportation the costliest mode?
air transportation can occur both domestically and internationally for passengers and freight.
air transportation is susceptible to weather conditions like fog, ice, heavy rain, and snow.
airplanes are capable of speeds between 500 and 600 miles per hour.
the cost of overhead for things like maintenance of aircraft and rent for airport space is extremely high, which impacts customer cost.

Explanation:

The question asks why air transportation is the costliest mode. The first option just states its scope (domestic and international for passengers and freight), which doesn't explain cost. The second option mentions susceptibility to weather, which is more about operational challenges rather than cost. The third option talks about speed, which is a performance aspect, not cost - related. The fourth option directly addresses cost factors like high overhead (maintenance of aircraft and airport space rent) that impact customer cost.

Answer:

The cost of overhead for things like maintenance of aircraft and rent for airport space is extremely high, which impacts customer cost.