In the reaction 3MnO2+4Al→3Mn+2Al2O3 ,the oxidising agent is :
MnO2
An oxidizing agent is referred to as a chemical compound that readily transfers oxygen atoms to other substance or a substance that gains electrons in a redox reaction. In the reaction, 3MnO2+4Al→3Mn+2Al2O3 , MnO2 behaves as an oxidising agent as it oxidises Al to Al2O3