Fehling's solution 'A' is

Solution & Explanation

\textbf{Answer:} (D) Fehling's solution 'A' is aqueous copper(II) sulphate. \textbf{Solution:} Fehling's reagent is prepared just before use by mixing two solutions: solution 'A' is aqueous copper(II) sulphate $\mathrm{CuSO}{}_4$, and solution 'B' is an alkaline solution of sodium potassium tartrate (Rochelle's salt). On mixing, a deep-blue cupric tartrate complex forms. Reducing sugars such as glucose reduce $\mathrm{Cu}{}^{2+}$ to red cuprous oxide $\mathrm{Cu}{}_2\mathrm{O}$. Hence option D is correct.