Final answer:
Watson and Crick's theory suggests that DNA replicates in a semiconservative manner, where each new DNA molecule consists of one original and one new strand, as supported by Meselson and Stahl's experiments.
Step-by-step explanation:
The theory advanced by Watson and Crick that explains the manner by which DNA replicates is the semiconservative model. This means that during replication, each double-stranded DNA molecule is composed of one original (parental) strand and one newly synthesized strand.
The experiments conducted by Meselson and Stahl provided strong evidence supporting this semiconservative replication model, which demonstrated that, after one round of replication, the DNA consisted of hybrid molecules each made up of one old and one new strand.According to this theory, each of the two parental DNA strands serves as a template for the synthesis of a new DNA strand. After replication, each double-stranded DNA molecule consists of one parental or "old" strand and one "new" strand.