The earliest discovered fossils are of ________ dating back to ________ years ago.
A. single-celled eukaryotes; 4.5 billion
B. prokaryotes; 3.5 billion
C. algae; 1 billion
D. fish; 600 million
Answer:B
The earliest discovered fossils are of ________ dating back to ________ years ago.
A. single-celled eukaryotes; 4.5 billion B. prokaryotes; 3.5 billion C. algae; 1 billion D. fish; 600 million