44. What releases the highest level of greenhouse gases in the environment? 1. Regular use of old air-conditioners 2. Dumping air-conditioners with coolants 3. Dumping air-conditioners without coolants 4. Poor maintenance of air-conditioners 45. What does ―that‖ (paragraph 4) refer to? 1. The leakage of F-gases 2. Information from the UN 3. Poor maintenance 4. Air-conditioning