The table that provides the best approximation of an organism's DNA base composition according to Chargaff's research is the third table.
Chargaff's research
Chargaff, in his research, found that the ratio of purine to pyrimidine bases for virtually all DNAs is constant.
Specifically, Chargaff found that the ratio of Adenine base to Thymine base is always the same. In the same vein, the ratio of Cytosine to Guanine base is always the same.
Thus, if a DNA contains a 21.2% Adenine base, the percentage Thymine base of in the DNA will also be 21.2%. This is for a fact.
In addition, the remaining percentage bases of the DNA must be shared equally between Cytosine and Guanine.
Only table 3 fulfills these conditions.
More on Chargaff's rule can be found here: https://brainly.com/question/14083251
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