Can some one help me I don’t know what to take out from the aspirin molecule, for the following structures?

I have to generate a copy of the molecular structure of aspirin and then for each of the molecular features listed in (i) – (iii) have to produce a related structure which, if synthesised and tested, would show the importance of the molecular feature of the aspirin molecule, in its action of relieving pain.

(i)the carboxylic acid group
(ii)the size of the hydrocarbon group on the ester.
(iii)the distance between the oxygen atom joined to the ring and the –OH group of the carboxylic acid.

Have to write a brief explanation of how each of the structures enables the importance of the molecular feature to be determined. No more then 50 words for each case. I have to change only one feature of the aspirin molecule at a time to produce each of the three compounds to be tested and to make sure that the valencies of all the atoms are correct in the new structures.

Science help needed here.

And I have already answered this..