22) using x-ray crystallography, as well as other methods, the researchers watson and crick discovered the structure of dna.

The correct answer for the blank is-

Double helix structure of DNA.

M. Wilkins and R. Franklin obtained high-resolution images of DNA fibers with the help of X-ray crystallography, which suggested other scientists like Watson and Crick to discover a double helical structure of DNA ( deoxyribonucleic acid). In other words, using the information of the work done by these two scientist, Wastson and Crick discovered double helical structure of DNA.