Answer: Option [B]
Wilkins X-ray diffraction showed the diameter of the DNA helix as 20A. Wilkins X -ray diffraction showed the diameter of the DNA helix is around 20A. According to Maurice Wilkins, the structure of DNA of all species comprises two helical chains each coiled round the same axis, and each with a pitch of 34 angstroms and a radius of 10 angstroms. According to another study, when measured in a particular solution, the DNA chain measured 20 to 26 angstroms wide, and one nucleotide unit measured 3.3 long. Although each individual repeating unit is very small, DNA polymers can be very large molecules containing millions of nucleotides.