我国幅员辽阔、人口众多、自然景观差异较大．读我国疆域示意图，图中所示黑河﹣腾冲线是我国的（    ）

A

    An Englishman was showing a foreign visitor around London.“What's that strange building?” asked the visitor.“That's the Tower (塔) of London.”“I see. How long did it take to build it?”“About 500 years.”“In my country we can build it in a few months.”said the visitor. After they came to St. Paul's Cathedral (大教堂), the visitor asked the same question. “Nearly forty years,”said the Englishman. “In my country we finish it in forty days at most,” said the visitor. This went on all day. They visited most of the best known buildings in the city. Every time they saw a new one, the visitor asked what it was and how long it took to build it. Then he said they could do the same thing much faster in his country. At last the Englishman got angry with the visitor though he tried not to show it. Several days later they came to the House of Parliament (议会) and the visitor asked his usual question, “What's that?” The Englishman answered, “I have no idea. It wasn't there last night.”

根据短文内容，选择正确答案。

我国生物多样性面临威胁的原因很多．根据以下资料对应写出生物多样性面临威胁的原因．

资料1：在淮河流域，由于污染不断加剧，于1994年爆发了特大污染事故，致使洪泽湖1200万千克鱼、9万千克蟹、2.5万千克虾死亡．著名的京杭大运河污染也很严重，目前，苏南大部城市河段发黑发臭，成为没有动物的“死河”．

资料2：200年前，澳大利亚从欧洲引进几只家兔供人观赏，一次突发火灾，家兔逃出木笼成为野兔．不到100年，已遍布澳大利亚大陆，成了破坏庄稼，与牛羊争食牧草，影响交通安全的祸害．

资料3：19世纪初，在美洲东部森林中的旅鸽数量非常多，成群飞翔时遮天蔽日，数量以亿万计．由于滥猎乱捕，每年被捕杀的旅鸽数以百万计，加上森林遭到严重破坏，绝大多数旅鸽被无情地杀死了，到1900年前后从野外消失．养在美国辛辛那提动物园里的最后一只旅鸽死于1914年．

材料4：据2010年5月27日的《人民日报》报道，由于长期过度放牧，内蒙古乌拉特草原正在大面积地退化为黄褐色荒漠．草原退化给鼠类提供了良好的栖息地，鼠害成灾，满地的鼠洞破坏了土层结构，加速草原沙化．同时，由于狐狸、老鹰、蛇等鼠类的天敌少，使鼠类更加泛滥，进一步加剧了对草原生态系统的破坏．