The correct option is D Wilkins and Franklin
Watson and Crick gave double helical structure of DNA. The challenge was to explain the X-ray data obtained by X ray crystallography experiments conducted by Maurice Wilkins and Rosalind Franklin and the biochemical data obtained by Erwin Chargaff. Jacob and Monod gave the operon concept to explain principles of gene regulation. Beadle and Tatum are known for 'one gene one enzyme concept'
So, the correct answer is 'Wilkins and Franklin'