Turtles have an unfortunate habit of eating plastic objects floating in the sea. These then get trapped in their alimentary cana

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问题     Turtles have an unfortunate habit of eating plastic objects floating in the sea. These then get trapped in their alimentary canals, cannot be broken down by the animals’ digestive enzymes and may ultimately kill them. It is widely assumed that this liking for plastics is a matter of mistaken identity. Drifting plastic bags, for instance, look similar to jellyfish, which many types of turtles love to eat. Yet lots of plastic objects that end up inside turtles have no resemblance to jellyfish. Joseph Pfaller of the University of Florida therefore suspects that something more complicated is going on. As he writes in Current Biology, he thinks that the smell of marine micro-organisms which colonize floating plastic objects induces turtles to feed.
    The idea that the smell of plastic rubbish might lure animals to their doom first emerged in 2016. Researchers at the University of California, Davis, noticed that certain chemicals, which are released into the air by micro-organism-colonized plastics, are those which many seabirds sniff to track down food. These chemicals mark good places to hunt because they indicate an abundance of the bacteria that lie at the bottom of marine food chains. The researchers also found that birds which pursue their food in this way are five or six times more likely to eat plastic than those which do not.
    Since turtles are known to break the surface periodically and sniff the air when navigating towards their feeding areas, Dr. Pfaller theorized that they are following these same chemicals, and are likewise fooled into thinking that floating plastic objects are edible.
    To test that idea, he and his colleagues set up an experiment involving loggerhead turtles, a species frequently killed by plastic. They arranged for 15 of the animals, each around five months old, to be exposed, in random order, to four smells delivered through a pipe to the air above an experimental area. Two of the smells proved far more attractive to the animals than the others. When sniffing both the smell of food and that of five-week-old bottles turtles kept their noses out of the water more than three times as long, and took twice as many breaths as they did when what was on offer was the smell of fresh bottle-plastic or clean water vapour. On the face of it, then, the turtles were responding to the smell of old bottles as if it were the smell of food.
    Though they have not yet tested whether the chemical is the culprit, Dr. Pfaller and his colleagues think it is the most likely candidate. In an unpolluted ocean, pretty well anything which had this smell would be edible—or, at least, harmless. Unfortunately, five-week-old plastic bottles and their like are not.
According to the experiment, which of the following is most attractive to turtles?

选项 A、bottles drifting for several weeks
B、freshly-thrown plastic bottles
C、unpolluted water vapour
D、the smell of rubbish

答案A

解析 根据题干关键词the experiment和most attractive定位到文章第四段第三、四句。第三句指出试验中有两种气味比其他气味更吸引动物;第四句详细说明海龟在闻到食物的气味和浸泡几个星期的瓶子的气味时,浮出水面的时间和呼吸频次会远远大于闻到干净的塑料瓶和水蒸气的气味,由此可知海龟最喜欢的味道是前面两种,对比四个选项可知,A项bottles drifting for several weeks(漂浮了几周的瓶子)属于前面两种之一,故为正确答案。B项freshly—thrown plastic bottles(新丢的塑料瓶)和C项unpolluted water vapour (未污染的水蒸气)属于后两种味道,所以不正确;D项the smell of rubbish(垃圾的味道)原文并未提及,故可排除。
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