Answer:
b
Step-by-step explanation:
There were three models for how organisms might replicate their DNA: semi-conservative, conservative, and dispersive.
The semi-conservative model, in which each strand of DNA serves as a template to make a new, complementary strand, seemed most likely based on DNA's structure.
The models were tested by Meselson and Stahl, who labeled the DNA of bacteria across generations using isotopes of nitrogen.
From the patterns of DNA labeling they saw, Meselson and Stahl confirmed that DNA is replicated semi-conservatively.
Mode of DNA replication
Imagine yourself in 1953, after the double helix structure of DNA has just been discovered^1
1
start superscript, 1, end superscript. What burning questions might be on your mind, and on the minds of other scientists?
One big question concerned DNA replication. The structure of the DNA double helix provided a tantalizing hint about how copying might take place^{1,2}
1,2