Answer:
A) one intermediate band
Explanation:
Meselson & Stahl experiment on the E.coli bacteria to identify the mechanism of replication in bacteria.
For this, they grew bacteria in a heavy isotope of the nitrogen šâľN which allowed the bacteria to take šâľN in their DNA. They then grew the bacteria into šâ´N which allowed the bacteria now to take šâ´N in their DNA.
When they allowed the bacterial population to replicate their genome for one generation they found that their genome contained both types of isotopes of nitrogen in their DNA through centrifugation.
Since after the centrifugation only one band was observed which contains both the form of the nitrogen, therefore, the band was called intermediate band with intermediate density.
Thus, Option-A is the correct answer.