Yes I believe that is true
Answer:
To be honest, I would say the best answer is the fact that flies move so you can't be sure if you counted a fruit fly or not. If this is a test i am sorry if you get it wrong, if its homework this is what I would've put.
It flickers or appears to flicker because of the long distance it hast to travel
I think the answer would be soot appears on a fireplace after a fire. I hope this helps you out! Good luck!
