Final answer:
Rosalind Franklin's X-ray diffraction studies were critical for Watson and Crick's construction of the DNA model, revealing the double helix structure.
Step-by-step explanation:
The X-ray diffraction studies critical to the work of Watson and Crick in constructing their model of DNA were carried out by Rosalind Franklin. In the 1950s, at the University of Cambridge, England, Francis Crick and James Watson were working to determine the structure of DNA. They and other scientists, such as Linus Pauling and Maurice Wilkins, made significant contributions to the field, but it was Franklin's X-ray diffraction images that were crucial in revealing the double helix structure of DNA. Franklin's data allowed Watson and Crick to piece together the DNA molecule's structure, leading to the formation of the double-helical model. Despite Franklin's vital contributions, she was not recognized with the Nobel Prize in Medicine awarded in 1962 to Watson, Crick, and Wilkins due to her untimely death.