已知甲、乙两组数据的平均数分别是X_甲=80，X_乙=90，方差分别是S_甲²=10，S_乙²=5，比较这两组数据，下列说法正确的是（　　）

    The history of air conditioners (空调) started in the early days with the need to preserve food. The food____is kept at room temperature spoils easily due to the growth of bacteria. At temperature below 4°C, the growth of bacteria reduces____(rapid). As a result of the development in food refrigeration, other following applications include air conditioning and manufacturing processes.

    The____(discover) of the principles of the absorption type of refrigeration in 1824 showed that liquefied ammonia (液氨) could cool air. At first, the commercially available use of air conditioning applications was based on the need to cool air for industrial processes rather than ____(person) comfort. The first electrical air conditioning____(invent) by Willis Haviland Carrier in 1902. He was also known____the Father of Modern Air Conditioning.____ (he) invention was designed to improve the manufacturing process of a printing factory. By____(control) the temperature, the process was made more efficient.

    The Carrier Air Conditioning Company of America was set up by him ____(meet) the demand of better productivity in the workplace. Today, Carrier Corporation is____biggest air conditioner manufacturer and marketing corporation in the world in central air conditioning.

请阅读下面两则材料，按要求答题。

       材料一：为解决山区高海拔地区中小学生冬季取暖问题，2015年6月，重庆市政府启动了“暖冬计划”。该计划实施范围是全市海拔800米以上的中小学校和公办幼儿园，涉及21个区县995所学校，受益学生21万余名。主要措施包括购置安装油灯、碳晶墙暖电热饭、电烤炉、暖风机、硅晶电热膜等取暖设备，少数有条件的学校可安装空调，不宜安装取暖设备的学校提供御寒所需衣服、鞋子、手套等物资。截至2015年底，全市共投入8700多万元，为山区农村学生创造出安心学习的温暖环境。学生张薇说：“现在教室安了油灯，像春天一样温暖。冬天再也不用提火盆上学了，手也不长冻疮了！”

       材料二：“暖冬计划”实施后，孩子们出于好奇，一下课就争先恐后地去触摸取暖片，很容易烫伤手或触电。老师一方面要担心学生的安全，另一方面还要担心取暖设备的保护问题。