Specify the functional groups by letters (A to G) as given in the list below. Use only one letter per box. If there are fewer than three functional groups, leave the appropriate number of answer boxes empty. If a functional group is present MORE than once, provide ONLY ONE entry for these groups.)

CH3-HC(NH2)-CO-OH

(a) hydroxyl group in alcohol
(b) amino group
(c) aldehyde group
(d) ketone group
(e) carboxyl group
(f) ester group
(g) amide group