单选题：根据下列文章,请回答题。Monarch without a KingdomThis November, a hundre

根据下列文章,请回答题。Monarch without a KingdomThis November, a hundred million butterflies will drop from the sky over Mexico, like autumn lea ves. But for how long? Genetically modified maize (玉米) could mean extinction for this beautiful butterfly, Ra fa el Ruiz reports.
Although its body is about 3 cm long and it only weighs 1 gm, the Monarch butterfly mana ges to tra vel 5,000 km each year. It seems to be so fra gile, but its long journeys are proof of its a ma zing ability to survive. This autumn, the Monarch butterfly will once more set out on its journey from the US. It will keep going until it reaches Mexico. It tra vels these huge distances to escape the cold weather in the north.
In November, millions of Monarchs fall like bright, golden rain onto the forests in the mountains of central Mexico. In the silence of these mountains you can hear astrange flapping (拍动) of wings, as the Monarchs arrive at their destination. In the mountains, which reach a height of 3,000 metres, the butterflies are sa fe.
Before reaching their journey's end they ha ve faced strong winds, rain and snowstorms and they do not all mana ge to reach their destination. When the winters are really bad, perhaps 70 per cent of them will not survive. Their long journey to Mexico is thought to be one of the most a ma zing events in the whole of the American continent. When they get there they will stay until the beginning of April, when their internal calendar tells them that it is time to go back. The long journey, with all its dangers, begins a gain.
These delicate creatures now face danger of another kind - from scientific progress.In the US, millions of farms grow genetically modified maize which is pure poison for the butterfly. Laboratory experiments ha ve shown that half of the butterflies which feed on the lea ves of genetically modified maize die within 48 hours. Not all experts a gree that this variety of maize is responsible for the threat to the Monarchs. In spite of these doubts, the European Union has refused to approve new crops of genetically modified maize until further investigations ha ve been carded out.
Greenpeace is ca mpaigning a gainst genetically modified products (in Spain, there are already 20,000 hectares of modified maize). The environmental organization recently published alist of 100 species of butterfly in Europe alone which are threatened with extinction.The Monarch butterfly tra vels 5,000 km each year. A．Right
B．Wrong
C．Not mentioned