The origin of human life can be traced to

Options

A. two cells
B. a single cell
C. many cells
D. no cell at all

Answer

B

Explanation

All life on the Earth evolved from a single-celled organism that lived roughly 3.5 billion years ago, a new study seems to confirm. The study supports the widely held "universal common ancestor" theory first proposed by Charles Darwin more than 150 years ago.