Answer: 4.5 billion years.
- A 4.5 billion years
- B 2.5 billion years
- C 4.5 million years
- D 450 million years
Correct answer: A. 4.5 billion years
Explanation: The Earth is estimated to have formed about 4.5 billion years ago, with life appearing a few hundred million years later.
A simple phylogenetic tree: a common ancestor branches into several descendant lineages over time, with each branch point marking a speciation event.
Concept context
Origin of life, Darwin's theory, natural selection, speciation, and evidence for evolution.