Bacteria were cultured in a medium that contained $^{15}\text{N}$. After a number of generations, every bacterial DNA molecule contained $^{15}\text{N}$. Some of these bacteria were then moved into a medium containing the usual nitrogen isotope, $^{14}\text{N}$. They were allowed to undergo one division. DNA from some of these bacteria was removed and analysed. This DNA consisted entirely of hybrid DNA with equal quantities of $^{14}\text{N}$ and $^{15}\text{N}$. The rest of the bacteria remained in the $^{14}\text{N}$ medium and were allowed to divide once again. DNA from some of these bacteria was then extracted and analysed. What is the percentage of hybrid DNA?
- A25% hybrid DNA
- B50% hybrid DNA
- C75% hybrid DNA
- D100% hybrid DNA