The experimental proof for semi-conservative replication of DNA was first shown in a

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Correct option is B

The experimental proof of semi-conservative mode of DNA replication was shown first in Escherichia coli (bacterium) by Matthew Meselson and Franklin Stahl and subsequently it was also exhibited in higher organisms, such as plants and human cells. In semi-conservative DNA replication, the two strands of DNA would separate and act as a template for the synthesis of new complementary strands. After the completion of replication, each DNA molecule would have one parental and one newly synthesized strand.