Final answer:
The fact that all organisms have DNA provides strong evidence for a common ancestor. DNA is a hereditary molecule that contains the genetic information for all living organisms.
Step-by-step explanation:
The fact that all organisms have DNA provides strong evidence for a common ancestor. DNA is a hereditary molecule that contains the genetic information for all living organisms. The similarities in DNA sequences between different organisms indicate a shared ancestry and evolutionary history. For example, comparing DNA sequences can show how humans and apes are related based on their DNA sequences. Therefore, the presence of DNA in all organisms supports the idea that they all originated from a common ancestor.