Meselson and Stahl were able to identify the semi-conservative replication of DNA by using labeled nitrogen isotopes. Which of the following reflects the result of their investigation that proves that DNA undergoes a semi-conservative replication process?

• A. DNA replication results in one molecule that consist of the original DNA strand and one molecule that consist of the new strands.
• B. DNA replication results in two molecules in which the individual strand is a patchwork of original and new DNA.
• C. DNA replication results in two molecules of the original strand.
• D. DNA replication results in two molecules with one original strand and one new strand.

Answer: (D)