Final answer:
The most correct representation of a combustion reaction among the given chemical equations is option B, 2Mg + O₂ → 2MgO.
Step-by-step explanation:
The most correct representation of a combustion reaction among the given chemical equations is option B. Combustion reactions involve the reaction of a fuel (usually a hydrocarbon) with oxygen to produce carbon dioxide and water. In option B, the equation 2Mg + O₂ → 2MgO represents the combustion of magnesium with oxygen to form magnesium oxide.