参考答案：A

解析：
A heater is using convection when it warms the air in a room. And the air in turn warms the people and objects in the room. A hot water radiator, a stove and forced air furnace are all convection heaters. A quartz heater, on the other hand, heats the objects and people in a room without heating the air. It does this by producing radiation heat that travels like light waves. The radiation is then directed at objects by means of a reflector.

[分析]： 原文介绍了几种散热器，其中重点介绍了quartz heater(石英散热器)。在描述该物时，说话者介绍“A quartz heater, on the other hand, heats the Objects and people in a room without heating the air.”即“而石英散热器在温暖房中的人和物时，却不会加热房中的空气”，选项A的说法与原文相符，因此是正确答案。
[解题关键] 识别信号词有助于迅速解题。文中谈到几种传统的散热器后使用了短语on the other hand这个表对比的词组来介绍石英散热器，由此可推测该物与前面提到的散热器肯定不同，通过背景常识，可帮助我们迅速猜测选项A有可能是正确答案。