Correct Answer - D
It was only in 1953 that James watson and Francls Crick, based on the X-ray diffraction data produced by Maurica Wllkins and Rasallnd Franklln, proposed a very simple but famous double helix model for the structure of DNA
Erwin Chargaff observed that for a double-stranded DNA, the ratios between adenine and thymine and guanine and cytosine are constant and equals one .
On the other bond Matthew Meselson and Franklln Stahl in 1958 performed experiments on E.coli to prove that DNA replication is semi-conservative. But had no contribution it the development of double helix model.
