Answer:
C. use hydrogen sulfide or organic compounds as a source of electrons.
Explanation:
Anoxygenic phototrophs are the ones that do not use a water molecule as a source of an electron during the process of photosynthesis. Â
Since these organisms do not exhibit splitting of water during photosynthesis, there is no release of oxygen as a by-product of photosynthesis.
Anoxygenic phototrophs are the ones that use organic or inorganic chemicals as a source of electron for light reactions of photosynthesis. Â
For example, purple and green sulfur bacteria preferably use hydrogen sulfide as an electron donor and oxidize it into elemental sulfur or sulfates. Â