The correct answer is: D. Exothermic reaction.
An exothermic reaction is a chemical reaction that releases energy in the form of heat. This is the opposite of an endothermic reaction, which absorbs energy. Combustion is a type of exothermic reaction that occurs when a fuel is combined with oxygen to produce heat and light. In the case of a candle, the fuel is wax and the oxygen is in the air. When the wick is lit, the heat from the flame causes the wax to melt and vaporize. The vaporized wax then combines with oxygen in the air to form carbon dioxide and water vapor. This reaction releases a large amount of heat, which keeps the candle burning.
A photochemical reaction is a chemical reaction that is initiated by light. This type of reaction is often used in photography and in the production of certain chemicals.
A physical change is a change in the state of matter, but not in the chemical composition of the matter. Examples of physical changes include melting, freezing, boiling, and evaporation.
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