Answer:
The correct answer will be option-B
Step-by-step explanation:
Stromatolites are the sedimentary deposited mounds made of layers of phototrophic microbes which were usually present in the primordial times. The stromatolites are one of the oldest fossils is known today which were formed in the shallow water.
They are composed of the phototrophic bacteria or cyanobacteria which survived and still survive by using the carbon dioxide and sunlight to make food material.
Since the bacteria are the prokaryotic organism therefore, the Option-B is the correct answer.