Microbial cells first evolved on Earth approximately ________ billion years ago.
A. 1.6 to 1.8
B. 3.8 to 3.9
C. 5.4 to 5.6
D. 7.0 to 7.2
Answer:B
Microbial cells first evolved on Earth approximately ________ billion years ago.
A. 1.6 to 1.8 B. 3.8 to 3.9 C. 5.4 to 5.6 D. 7.0 to 7.2