阅读下列短文，从文后各题所给的四个选项中选出一个最佳答案。

    1 years and years people have been saying that railways are dead. “We can do 2  railways,” people say, 3 cars and planes have made railways unnecessary. We all keep hearing that trains are slow, 4  money and are dying. But this is far from the 5 . In these days of expensive 6, railways have become highly competitive（竞争的）with cars and planes. If you want to carry people or things from place to place, they're 7 than planes. And they have much in 8 with planes. A plane goes in a straight line and 9 does a railway. What is more, a railway takes you from the heart of a city center. It doesn't stop as a car does on crowded roads. And no plane or car can ever carry as many goods(货物) as one train 10.

    Far from being dead, railways are much 11. Modern railway lines give you a comfortable journey. Where else can you eat well, sleep comfortably, feel safe and enjoy the scene while you are traveling 12? And we are only the beginning, for we have just  13 the age of super-fast trains, which can travel almost 200 14 an hour or more. Soon we will be wondering 15 we spent so much on highways and planes we can't fly in because we don't have enough money to buy the oil.

下列生物中，没有细胞结构的是（ ）