Final answer:
Watson and Crick based their model of DNA on X-ray crystallography from Rosalind Franklin and Maurice Wilkins, uncovering the double helix structure, although Franklin's crucial contributions were only recognized posthumously. The correct option is (a).
Step-by-step explanation:
The Watson and Crick model of DNA is based on the X-ray crystallography provided by Rosalind Franklin and Maurice Wilkins. Watson and Crick formulated the double-stranded structural model of DNA after analyzing X-ray diffraction images of DNA, which revealed the molecule's helical nature.
While Watson and Crick received the Nobel Prize in 1962 for their discovery, the essential contributions of Franklin, whose work captured the critical X-ray diffraction images, are recognized as foundational for piecing together DNA's double helix structure. Unfortunately, Franklin did not receive the same acclaim during her lifetime due to her untimely death prior to the Nobel recognition and the policies of the Nobel Prize committee at the time.