During which reaction is the organic compound oxidised?
- A$ ext{CH}_3 ext{CH}_2 ext{OH}$ + concentrated $ ext{H}_3 ext{PO}_4$
- B$ ext{CH}_3 ext{CH}_2 ext{CH}_2 ext{CHO}$ + Tollens’ reagent
- C$ ext{CH}_3 ext{COCH}_3$ + 2,4-dinitrophenylhydrazine reagent
- D$ ext{CH}_3 ext{CN}$ + dilute $ ext{H}_2 ext{SO}_4$