A, the product of human anaerobic respiration is lactic acid, and the amount of oxygen absorbed during aerobic respiration is the same as the amount of carbon dioxide released, so the ratio of the amount of oxygen absorbed by human cells to the amount of carbon dioxide released is 1: 1, and so is marathon running. A is correct;

B, the analysis chart shows that the longer the running distance, the smaller the proportion of anaerobic respiration energy supply, and B is wrong;

C, the longer the running distance, the proportion of anaerobic respiration and aerobic respiration is equivalent, but because the energy released by anaerobic respiration is far less than that of aerobic respiration, the glucose consumed by anaerobic respiration is far more than that consumed by aerobic respiration in this process, C error;

D. According to the analysis chart, when running 100 meters, the required ATP is mainly produced by anaerobic respiration, and D is wrong.

So choose: a.