In the aluminothermite process, aluminium acts as

detailed solution

Correct option is D

In aluminothermite process "Al" acts as reducing agent .→ " Al "acts as strong reducing agent.eg.,ALUMINO THERMITE PROCESSMixture of metal oxide and Al powder in 3:1 ratio is called Thermite mixture.Mixture of BaO2 and Mg or Al powder is called ignition mixture.Example for thermite mixture is, Fe2O3 and Al  3:1 ratio.→ On burning of Mg-ribbon, it carries the flame into ignition mixture.Ignition mixture on ignition provides huge amount of energy.By using this energy Al of thermite mixture reduces the metal oxide to metal. The metal obtained in this process will be in liquid state .This formed liquid metal (Fe) is used for welding of train rails and welding of other metals.