Answer:
A.Hot air rising,cold air sinking
Explanation:
Hot air rises in a confined or closed space.That is one of the reasons why firefighters have some people crawl on the flour to get out. the smoke is hot air so it rises to the ceiling of the room, while cold air stays lower.
Discovery of Bacteria and Other Achievements. Antony Leeuwenhoek was the first person to see bacteria. Through the late 1670s, he sent comprehensive data and detailed drawings of his sightings of bacteria and algae to the Royal Society in London.
Light that appears white or nearly white to humans is made up of spectrum of visible light i.e. combination of violet, indigo, blue, green, yellow, orange and red.