Answer: (1) single replacement
Explanation:
A single replacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution.Thus magnesium can easily lose electrons as compared to silver and result in the formation of magnesium nitrate and silver.
Double displacement is a chemical reaction in which ion exchange takes place.
Synthesis reaction is a chemical reaction in which two reactants combine to give a single product.
Decomposition is a chemical reaction in which one substance decompose to give two or more than two products.