Answer:
Option C
Explanation:
The cyanobacteria is the oldest life form that once existed on planet earth some 3.7 billion years ago. These cyanobacteria formed layered structures fossils which are called as stromatolites
Hence, stromatolites are the fossilized colonies of cyanobacteria.
A set of rocks in Greenland show the evidence of cyanobacteria as a living organism.
These stromatolites have layered structure of bio-chemical accretionary that are produced by trapping sedimentary grains through biofilms of microorganisms such as cyanobacteria.
Hence, option C is correct