The correct option is C AgNO3(aq)+NaCl(aq)→AgCl(s)+NaNO3(aq)
The reaction in which exchange of ions takes place between the compounds of the reactants is called a double displacement reaction.
The reaction between silver nitrate and sodium chloride involves exchange of their ionic counter parts to form the product. Hence, it is a double displacement reaction.
All the other three reactions given are combination reactions. Combination reaction is a reaction in which two or more elements or compounds combine to form a new product.