Concept:Calcium carbide reacts with water to produce acetylene gas, which burns to give a very hot flame.Explanation:When water is added to calcium carbide, the reaction is:CaC2+2H2O→C2H2+Ca(OH)2The gas released is acetylene, C2H2.This gas is passed through a jet and lighted.Acetylene burns in oxygen to form a flame with extremely high temperature.That flame is known as the oxyacetylene flame.It is commonly used for welding and cutting metals.Answer:C. Oxyacetylene flame.