Harry Hess was a professor of geology at Princeton and soon became interested in geology of oceans while serving in the navy. He used the opportunity ,of being in the navy, to use echo sounding to map the ocean floor. In 1962, he published "The history of ocean basins" which outlined the theory called 'Sea floor spreading' that explained how continents could drift. He found out that oceans were more shallow in Mid ocean ridges, which were raised above the abyssal plain. He also found out that the deepest parts of the oceans were close to continental margins with trenches in the ocean leading down to depths of over 11 kilometers in the Marianas Trench. Hess believed that ocean trenches were where the ocean floor was recycled after being destroyed.
It’s most likely A, pet dander. If the inside of your house is being polluted by gasoline and asbestos you’ve probably got some serious issues. Hope this helps.
