Respuesta :
Answer:
Prokaryotes
Explanation:
The earliest form of life on earth appeared some billion years ago and consisted of prokaryotes. These prokaryotes primarily contains bacteria, archaea and other microscopic organisms that were single celled and have no nuclei. Most of these prokaryotes were anaerobic as they lived in an environment in which there was no oxygen. Instead of oxygen they used other constituents of atmosphere like sulfur, nitrogen etc.
