Answer:
The answer to your question is the letter C) Synthesis.
Explanation:
Data
H₂ and O₂ produces water
Balanced chemical reaction
2H₂ + O₂ ⇒ 2H₂O
Definition of the kinds of reactions
A) double-displacement is a reaction where the cations and anions of the reactants are interchanged.
B) endothermic is the chemical reaction that needs a supply of energy to proceed.
C) synthesis is the chemical reaction where two reactants combine to form only a product.
D) combustion is the chemical reaction where a compound with carbon reacts with oxygen to form carbon dioxide and water.
Conclusion
From the information given we conclude that the reaction between hydrogen and oxygen is a synthesis reaction.