Banzaldehyde can be prepared slectively by
A. `"Toluene"underset((CH_(3)CO)_(2)O)overset(CrO_(3))rarr`
B. `"Toluene"underset((CH_(3)CO)_(2)O)overset(CrO_(2)Cl_(2))rarr`
C. `"Toluene"underset(KOH_(aq.))overset(KMnO_(4))rarr`
D. `C_(6)H_(5)CH_(2)OHunderset("Pyridibne"//HCl)overset(CrO_(3))rarr`