What do anaerobic organisms have in common with photosynthetic organisms?

a.) they both appeared on earth at about the same time.
b.) they both can only exist as single-celled organisms.
c.) they both need an energy source in order to survive.
d.) they both produce carbon dioxide as a waste product.

Ans is option C. They both need an energy source in order to survive.

Energy is an absolute necessity to survive on this earth. All living organisms need energy be it anaerobic or photosynthetic.  Photosynthetic organisms can make their own food in the presence of sunlight by photosynthesis and harness energy from it. Anaerobic organisms can also make their own food in the absence of sunlight with the help of inorganic molecules like hydrogen sulfide (H2S), ammonia (NH3), sulphur (S) etc.

Its just that anaerobic organism's way of harnessing energy is different from those of aerobes/photosynthetic organisms but they need energy source for sure.

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.