Final answer:
Franklin's Photo 51 provided crucial evidence for the double helix structure of DNA.
Step-by-step explanation:
In Franklin's Photo 51, we learned about the structure of DNA. Photo 51 was an X-ray diffraction image taken by Rosalind Franklin that provided critical evidence for the double helix structure of DNA. This image helped scientists like Watson and Crick to unravel the secrets of DNA and understand its role in heredity and genetics.