Answer:
The correct answer is - 2.5 billion years ago.
Step-by-step explanation:
The life on the earth has evolved with 3 different lineage namely Bacteria, Eukarya, and Archaea. However the 2 are prokaryotic groups of microbes that lack membrane bound organelles and nuclei.
Recent studies suggested that these two domain, Eukarya and the Arcahea are more close than the bacteria domain. These two domains are shared the common ancestor that probably existed 2.5 billion years ago.
Thus, the correct answer is - 2.5 billion years ago.