Which property of DNA double helix led Watson and Crick to hypothesise semi-conservative mode of DNA replication? Explain.

The property of DNA double helix that led Watson and Crick to hypothesise semi-conservative of DNA replication was that the two strands in the DNA are complementary and anti-parallel based on their base sequences. They suggested that the two strands would separate and act as a template for the synthesis of new complementary strands. After the replication, each DNA molecule would have one parent strand and one newly synthesized daughter strand.