Q. Which among the following is the most primitive life form?
Answer: Bacteria
Notes: The most primitive life forms on Earth are prokaryotes, which are the simplest cellular forms of life. Prokaryotes include archaea and bacteria, which have been found on Earth for 3.5 to 3.8 billion years. The earliest known life forms on Earth are fossilized microorganisms found in hydrothermal vent precipitates. These microorganisms are believed to be about 3.42 billion years old. The first life forms were probably a tiny bacteria called archaebacteria. These bacteria thrive in very hot, chemically rich places.