Three molecular ionic states, P-R are possible for the amino acid histidine. Identify the correct choice of pH values, respectively for the observation of the ionic states P-R.

A. CH₃C$${\text{O}}_2^ - $$ > CH₃O^- > C₆H₅O^- > N$${\text{O}}_3^ - $$ B. CH₃O^- > N$${\text{O}}_3^ - $$ > C₆H₅O^- > CH₃C$${\text{O}}_2^ - $$ C. CH₃O^- > C₆H₅O^- > CH₃C$${\text{O}}_2^ - $$ > N$${\text{O}}_3^ - $$ D. C₆H₅O^- > CH₃O^- > N$${\text{O}}_3^ - $$ > CH₃C$${\text{O}}_2^ - $$

A. (i) peracid, (ii) H⁺, (iii) Zn/dil.HCl B. (i) Alkaline KMnO₄, (ii) NalO₄, (iii) N₂H₄/KOH C. (i) Alkaline KMnO₄, (ii) H⁺, (iii) Zn/dil.HCl D. (i) O₃/Me₂S, (ii) NaOEt, (iii) N₂H₄/KOH

A. CH₃CO₂H B. CH₃CONHC₆H₅ C. n-C₆H₁₃C ≡ CH D. n-C₆H₁₃CHO

A. reaction with sodium cyanide in the presence of nickel catalyst B. reaction with chloroform and sodium hydroxide C. diazotisation followed by reaction with CuCN D. reaction with ethyl formate followed by thermolysis