When an aqueous solution of D - glucose or D - mannose is treated with a base it undergoes some conversions. This conversion (isomerisation) involves
Both (a) and (b)
When an aqueous solution of D - Glucose , D - mannose or D - fructose is treated with a base, it undergoes enolization and a series of keto - enol tautomerization to form a mixture of the three monosaccharides (Lobry de Bruyn van Ekenstein tranformation). For reactions, consult text.