C.
The reason why is because it's talking about how much would it takes to make charcoal, which is a lot to yield so little charcoal. So, it's negative.
The answer to this is yes because diffusion is the movement of particles from high concentration to low concentration. As the smoke rises at one corner of the room soon it spreads all over the room which is simply diffusion.
To answer this question i would need to have more information on what you are dealing with. If you can link this with more information that would be great.
Answer:
You can take your time on tests, and when you're done check you're answer. You can read your essays backwards(when you do this your brain pays more attention because it is doing something different). You can finish work on time. You can ask for extra credit options. You can study for tests everyday(if you study before you go to sleep it helps you remember what you need to).
Explanation:
