Anoxygenic phototrophs a. produce oxygen. b. use water as a source of electrons. c. use hydrogen sulfide or organic compounds as a source of electrons. d. use the same form of chlorophyll found in terrestrial plants. e. produce oxygen and use the same form of chlorophyll found in terrestrial plants.

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.  

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.  

For example, purple and green sulfur bacteria preferably use hydrogen sulfide as an electron donor and oxidize it into elemental sulfur or sulfates.  

it has one origin of replication, but it proceeds in two directions - d)