Answer:
C. Bacteria breaks down ammonia into nitrogen
Explanation:
I know all about this, but could you specify what you mean?
X: Ozone layer destruction
Y: Mass extinction
Poor sanitation allows rodents to settle in
Improper storage of foods encourages them to stay
Removal of the rodents' predators, such as snakes, also allows population to rise
Former volcanoes now under the sea are called seamounts, or perhaps submarine volcanoes.
One of these two, and I'd say it's the first one.