Observe the given reaction scheme showing various methods for the...

Pathway P: The reduction of benzoyl chloride to benzaldehyde using $H_2$ in the presence of $Pd-BaSO_4$ is known as the Rosenmund reduction. Thus, A $\rightarrow$ 3.

Pathway Q: The reduction of benzonitrile to benzaldehyde using $SnCl_2$ and $HCl$ followed by acidic hydrolysis is known as the Stephen reaction. Thus, B $\rightarrow$ 4.

Pathway R: The oxidation of toluene to benzaldehyde using chromyl chloride ($CrO_2Cl_2$) is known as the Etard reaction. Thus, C $\rightarrow$ 1.

Pathway S: The reaction of toluene with $Cl_2$ in the presence of sunlight ($h\nu$) yields benzal chloride, which upon hydrolysis gives benzaldehyde. This is a side-chain chlorination reaction. Thus, D $\rightarrow$ 2.

The correct matching is (A)-(3), (B)-(4), (C)-(1), (D)-(2).

Answer: (A)-(3), (B)-(4), (C)-(1), (D)-(2)