The diagram below represents Meselson and Stahl's experiment on DNA replication.

For several generations, E. coli was grown in a medium containing an isotope of nitrogen, `N^(15)` . DNA was extracted periodically, at successive generations, and it was subjected to ultracentrifugation to check the percentage of the isotope that was transmitted across generations.
How did the centrifugation process help in providing evidence of the nature of DNA replication?

Options

A. It mixed the medium well.
B. It destroyed the heavy isotope.
C. It allowed the DNA with `N^(14)` to settle down.
D. It separated the DNA with nitrogen isotopes based on densities.

Answer

D