\(\mathrm{H_2S}\) contains 5.88% hydrogen, \(\mathrm{H_2O}\) contains 11.11% hydrogen while \(\mathrm{SO_2}\) contains 50% sulphur. These figures illustrate the law of:

This question uses laws of chemical combination, mole concept & particle counting. Compare the given data with the statements of the various laws; only one law is consistent with how composition changes, so option D is correct.