题目

阅读理解Yellowstone Weather Yellowstone National Park is at high altitude. Most of the park is above 7,500 feet (2,275 meters). Yellowstone's weather is unpredictable. In summer, it may be warm and sunny with temperatures in the high 70s. At night in any given month, the temperature may drop close to freezing. So it is best to come prepared for cold evenings and mornings, especially if you are camping or hiking. When you leave your campsite, please leave it prepared for possible thundershowers and wind. A sunny warm day may become fiercely stormy with wind, rain, sleet and sometimes snow. 冬天的雷鸟羽毛颜色和雪地颜色很相似，用达尔文进化论观点分析，这是（ ）A．人工选择的结果B．自然选择的结果C．雪把羽毛染白的结果D．不适应环境的表现