Which transport mode is the least air polluting (per tonne / km)?

Which transport mode is the least air polluting (per tonne / km)?
A . Road
B . Rail
C . Air
D . Sea

View Answer

Answer: D

Explanation:

Sea transport, although slow, because of the volumes and tonnage which can be included in a single shipment, comes out best in terms of pollution. Although, that is not to say sea transport is not pol-luting – quite the opposite. The second least polluting is rail – also primarily because of the load size.