Final answer:
Watson and Crick were the first to suggest semiconservative replication, and Meselson and Stahl's experiments later confirmed this model.
Step-by-step explanation:
The first to suggest semiconservative replication was Watson and Crick. This means that when DNA replicates, each of the two strands of the DNA molecule serves as a template for a new, complementary strand. The experiments conducted by Meselson and Stahl later provided the empirical evidence supporting this model.
Meselson and Stahl's experiments involved labeling DNA with heavy nitrogen isotopes and demonstrating that after one generation of replication in normal nitrogen, the DNA formed a hybrid band indicative of semiconservative replication. After a second generation, two bands were visible — one with hybrid DNA and the other with lighter DNA, further confirming the semiconservative nature of DNA replication. Thus, their experiments excluded the conservative and dispersive models of DNA replication.
In contrast, the Hershey and Chase experiments were focused on proving that DNA, not protein, was the genetic material, which is a different aspect of DNA's role in heredity.