There are many wetlands（湿地） in China and some of them have become the world‘s important wetlands. The Chinese Yellow Sea Wetlands are among them. They are in Yancheng， Jiangsu Province. They are home for many different kinds of birds and animals. The world’s largest Milu Deer Nature Reserve（自然保护区） is in them. More than 700 milu deer live freely there. There are not many red-crowned cranes in the world， but every winter you can see some in the Red-crowned Cranes Nature Reserve in the Yellow Sea Wetlands.
   The temperature in the wetlands is usually neither too high nor too low. There is a lot of rain and sunshine， too. They are really good places for wildlife（野生生物）。 Offering food and home for some special kinds of animals and birds is not the only reason why we need to protect wetlands. Wetlands are important because they also prevent flood. But some people want to change the wetlands to make more space for farms and buildings. This means there will be less and less space for wildlife.
   Luckily， more and more people are beginning to realize the important of wetlands and wildlife. Every year， on February 2nd， many activities are held to tell people more about wetlands.
根据以上短文内容，然后从每题所给的四个选项中选择最佳选项。

阅读下列材料，完成相关问题。

材料一  南海诸岛是中国神圣领土的一部分。西沙群岛地处热带中部，属热带季风气候，炎热湿润，但无酷暑。以永兴岛为例，极端高温34.9℃，极端低温15.3℃，年平均气温26.5℃。年降雨量1505毫米。西沙群岛是最易受台风侵袭的地区。

材料二  甘泉岛（北纬16°30'，东经111°35′）位于中国西沙群岛永乐环礁上，在珊瑚岛（注：珊瑚形成于温暖的浅海环境）西南2海里处，岛上有中国最南端的文物保护单位—西沙甘泉岛唐宋遗址。甘泉岛是西沙群岛中出露最晚的岛，地势较高，四周为沙堤围绕，岛中心由于湖干涸演化形成平地，周围珊瑚礁环绕；岛上有一口古井，井水清澈甘甜适宜使用，也是西沙为数不多具有淡水的岛屿。

材料三  南海诸岛及甘泉岛图。

一个菱形的两条对角线的长分别为5和8，那么这个菱形的面积是（   ）

如图，在△ABC中，∠A=50°，AD为∠A的平分线，DE⊥AB，DF⊥AC，则∠DEF=（　　）

在常温下发生下列反应，根据反应，判断下列结论中错误的是（   ）

（1）16H⁺+10Z^﹣+2XO₄^﹣═2X²⁺+5Z₂+8H₂O；（2）2A²⁺+B₂═2A³⁺+2B^﹣；（3）2B^﹣+Z₂═B₂+2Z^﹣．