In DNA molecule

According to Chargaff?s rule, in all cellular DNAs, regardless of the species, a number of adenosine residues is equal to the number of thymidine residues which means that A = T; and the number of guanosine residues is equal to the number of cytidine residues; G = C which makes option A incorrect. Hence, that the sum of the purine residues equals the sum of the pyrimidine residues, i.e., A + G = T + C; this means that purine to pyrimidine (A+G/T+C) or pyrimidine to purine ratio (T+C/A+G) is constant for a species; which makes option C incorrect. The same orientation of all phosphodiester linkages along the DNA chain imparts each linear nucleic acid strand a specific polarity and distinct 5? and 3? ends. The 5? end lacks a nucleotide at the 5? position thereby, having free phosphate group and the 3? end lacks a nucleotide at the 3? position thereby, having a free hydroxyl group. The 5? phosphate of one strand faces 3? hydroxyl group of other strand and that the 5? phosphate groups of two strands are present in opposite position; two DNA strands are antiparallel, i.e., not parallel; option D is incorrect and B is correct.

Thus, the correct answer is option B.