What types of evidence allow scientists to infer that single-celled life likely existed 3.8 billion years ago?

Which sequence represents a cross section of the bilayera hydrophilic head, hydrophobic tail, hydrophobic tail, hydrophilic headb hydrophobic tail, hydrophilic head, hydrophobic tail, hydrophilic headc hydrophobic head, hydrophilic tail. hydrophilic tail, hydrophobic headd hydrophilic tail, hydrophobic head, hydrophobic head, hydrophilic tail

This group of organisms perform the process of ammonifcation. a. herbivores b. decomposers c. carnivores c. plants

How energy flows through each level in this energy pyramid. is all the matter and energy from one level transferred to the next level?