Correct statements regarding 'D' is
It is called sulphonic acid
It exists as zwitter ion in aqueous solution
It is an amino acid
It is used as rubber in industry
A = C6H6; B = C6H5 - NO2; C = C6H5 - NH2; D = Sulphanilic acid
The α - amino acids, usually exist in the form of zwitter ions. It means they have: