The correct answer is The colour of the solution changes from colourless to blue and a silver solid deposits on copper wire.Concept:Displacement reaction:It is a chemical reaction wherein a more reactive element displaces the less reactive one from its salt solution.For example, CuSO4 + Fe ? FeSO4 + Cu, here Fe is more reactive than Cu.Explanation:Reactivity series: It refers to the arrangement of metals in the descending order of their reactivities.Copper is above silver in the reactivity series indicating that it is more reactive than silver. Thus, when a copper wire is dipped in silver nitrate solution, it will displace silver and form a blue-coloured copper sulphate solution.