Final answer:
The genomes of bacteria are most similar to those of the first living organisms on Earth.
Step-by-step explanation:
The correct answer is b. bacteria. The genomes of bacteria are most similar to those of the first living organisms on Earth. Bacteria are prokaryotic organisms that lack a membrane-enclosed nucleus and other membrane-bound organelles. They are simple, single-celled organisms that have been evolving for billions of years and have played a crucial role in the development of life on Earth.