单选题 When released into the atmosphere, the refrigerant Freon damages the Earth's ozone layer. A new kind of refrigerant does not have this effect. The manufacturer claims that replacing Freon with the new refrigerant in both new and existing refrigerators will prevent any further Freon damage to the ozone layer apart from that being done by the Freon already in the atmosphere.
Which of the following must be true if the manufacturer's prediction is to prove accurate?

【正确答案】 A
【答案解析】