Final answer:
Morgan and Sturtevant were the first to map a sequence of genes along a chromosome using crossing over frequency. Alfred Sturtevant created the first gene map in 1913 in Morgan's lab. Option a is correct answer.
Step-by-step explanation:
The individuals who were the first to use crossing over frequency to map a sequence of genes along a chromosome were Morgan and Sturtevant. In 1913, Alfred Sturtevant, a student in Thomas Hunt Morgan's laboratory, utilized the data from fruit fly (Drosophila) experiments to create the first gene map. He recognized that the frequency of crossing over during meiosis could be used to determine the relative positions of genes on a chromosome, laying the groundwork for chromosome mapping.
While Rosalind Franklin, along with Watson and Crick, made significant contributions to the understanding of DNA structure, their work did not involve the mapping of genes on chromosomes. Rosalind Franklin's critical contribution was through the use of X-ray diffraction methods to capture images, most notably Photo 51, which provided key insights into the double helix structure of DNA.
In contrast, Watson and Crick deciphered the structure based on Franklin's and others' findings. However, their work did not include gene mapping through crossing over frequencies.