(A) : Oxidation state of carbon in glucose is zero
(R) : Oxidation state of an atom in any element is zero

Oxidation state of C in glucose (C₆H₁₂O₆) is:

$$\begin{gathered} 6(\mathrm{oxidation} \mathrm{state} \mathrm{of} \mathrm{C})+12\left(1\right)+6(-2)=0 \\ 6(\mathrm{oxidation} \mathrm{state} \mathrm{of} \mathrm{C})=0 \\ \mathrm{oxidation} \mathrm{state} \mathrm{of} \mathrm{C}=0 \end{gathered}$$

Carbon is not present as element in glucose, it combined with O and H to form glucose.

Hence, A is right but R does not provide any relevant information regarding A.