题目内容：
根据以下资料回答题The five primary modes of transportation are rail, road, pipeline, water, and air.Each has different economic and service characteristics.( 41 )offers the cost -effective, energy- efficient transport of large quantities of goods over long distances.( 42 )offers more flexibility and versatility to the shipper than Virtually any other forms of transportation.( 43 ) are primarily used to move petroleum, natural gas, and chemicals.For suitable commodities, pipelines are the most efficient mode of transport.They offer a closed system with little risk of loss or damage to the products moved and extremely low cost.The most expensive of all the modes,( 44 ) offers the fast service but at a relative high price.( 45 )occurs on inland waterways and oceans.Though slower han other modes, this form of movement is also relatively inexpensive.
A．Rail transport B．Road transport
C．Truck transport
D．Air transport
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