Answer:
replacement
Explanation:
There are two types of replacement reactions.
Double replacement:
It is the reaction in which two compound exchange their ions and form new compounds.
AB + CD → AD +CB
Single replacement:
It is the reaction in which one elements replace the other element in compound.
AB + C → AC + B
The given reaction is double replacement reaction because anion and cation of both reactants exchanged with each other.
Other options are incorrect because,
Decomposition reaction:
It is the reaction in which one reactant is break down into two or more product.
AB → A + B
Synthesis reaction:
It is the reaction in which two or more simple substance react to give one or more complex product.
Oxidation:
Oxidation involve the removal of electrons and oxidation state of atom of an element is increased.
