text: <unk>  is a sugar<unk> , an oxidized form of D-galactose. It is the main component of pectin, in which it exists as the polymer polygalacturonic<unk> . It has an aldehyde group at C1 and a carboxylic<unk>  group at C6. Other oxidized forms of D-galactose are D-galactonic<unk>  (carboxylic group at C1) and meso-galactaric<unk>  (mucic<unk>  (carboxylic groups at C1 and C6
option_0: D-Galacturonic acid
option_1: Hypromellose
option_2: Pentose
option_3: Fructose
option_4: Trehalose
option_5: Heparan sulfate
option_6: Lecithin
option_7: Tetracosactide