Final answer:
The structure of DNA was discerned by Watson and Crick using X-ray crystallography, based on data from Rosalind Franklin and Chargaff's rules. They published their findings in 1953 and were awarded the Nobel Prize in 1962.
Step-by-step explanation:
The structure of DNA double helix was deduced by Watson and Crick using various experimental data, including that of X-ray crystallography of DNA. The correct answer to this question is option a) X-ray crystallography. Watson and Crick utilized X-ray diffraction data produced by Rosalind Franklin, which significantly contributed to the discovery of the double-helix structure. This combined with Chargaff's rules, another critical piece of evidence, allowed them to decipher the molecular structure of DNA. Their research led to the publication of their model of the DNA double helix in 1953, and for this monumental scientific achievement, Watson, Crick, and Maurice Wilkins received the Nobel Prize in Physiology or Medicine in 1962, after the unfortunate death of Rosalind Franklin, who passed away in 1958 and thus was not eligible for the Nobel prize.