Reagent used to convert allyl alcohol to acrolein is 

A moderate oxidising agent, manganese dioxide is utilised particularly to oxidise primary or secondary allylic and benzylic alcohol.
The equation for the reaction that generates allyl alcohol into acrolein is as follows:${\text{CH}}_{\text{2}}{\text{= CH - CH}}_{\text{2}}\text{OH }\stackrel{{\text{MnO}}_{\text{2}}}{\to }{\text{ CH}}_{\text{2}}\text{= CH - CHO}$
Therefore, the correct option is option (C)${\text{MnO}}_{\text{2}}$