Given below are two statements. One is labelled as Assertion (A) and the other is labelled as reason (R). 

Due to +R effect of benzene ring, the electron density in the carbonyl group of benzaldehyde increases. This in turn, increase the electron density in the C−H bond of aldehyde group. As a result, the C−H bond becomes stronger and hence only oxidising agent like Tolllens agent; [Ag(NH_3​)₂]⁺​ $\left({\mathrm{E}}_{{\mathrm{Ag}}^{+}/\mathrm{Ag}}^{\mathrm{o}}=0.8 \mathrm{V}\right)$ can oxidise C−H to C−OH to from carboxylic acids but weaker oxidising agent like Fehling's solution or Benedict's solution $\left({\mathrm{E}}_{{\mathrm{Cu}}^{2+}/{\mathrm{Cu}}^{+}}^{\mathrm{o}}=0.18 \mathrm{V}\right)$ fail to oxidies benzaldehyde to benzoic acid.