Most Ecosystems on Earth Rely on Sunlight as the Primary

Multiple Choice

Most ecosystems on Earth rely on sunlight as the primary energy source for the synthesis of organic compounds that living organisms need. Sunlight does not penetrate deep enough in the ocean to provide energy for organisms living near hydrothermal vents. How can these densely populated communities survive without energy from the sun?

A) chemoheterotrophic bacteria convert organic compounds into carbon dioxide which is used by other organisms as an energy source
B) chemoautotrophic bacteria harvest chemical energy from hydrogen sulfide and then provide the basis of food for the vent communities
C) chemoheterotrophic bacteria harvest chemical energy from hydrogen sulfide and then provide the basis of food for the vent communities
D) chemoautotrophic bacteria fix nitrogen which then is used as a source of energy for other organisms