Benzonitrile with $CH_3MgBr$ followed by hydrolysis gives acetophenone ($C_6H_5COCH_3$), a ketone, not benzaldehyde. Benzoyl chloride with $H_2$/Pd-$BaSO_4$ (Rosenmund reduction), ethyl benzoate with DIBAL-H, and toluene with $CrO_2Cl_2$ (Etard reaction) all give benzaldehyde.