It's not A or B because neither have any effect on air pollution. Air conditioners or heaters just change the temperature of the air by filling the room in. Products being reused or disposed makes no difference on air, although it can make a big impact on whether the environment stays green so to speak.
The answer is C.
Hazardous waste are different. They are dangerous, suffocating, and irritating. They are pretty much chemicals that people should be careful of using. It's even worse if it's not disposed of properly. The name hazardous itself explains the danger. It is something that can pollute the environment if not taken care of properly.
Though I'd only recommend an increase of handywork and skill, Out of the options above, i'd choose to use dull knives.
The advantages of seeing a specialist vs a primary care physician is that the specialist knows exactly about that field of medicine. One circumstance for a specialist: Your eye is bleeding and red, you might want to go see an ophthalmologist because they focus on the eyes. One circumstance for a primary care physician: You feel weak, dizzy and you are vomiting, you have no specific area of pain, so you might want to see a primary care physician because they know about different fields of medicine instead of just focusing on one.
