The correct option is D Double displacement reaction
In the reaction, sodium sulphate reacts with barium chloride to give barium sulphate as white precipitate along with sodium chloride.
The precipitate so formed is because of the exchange of ions between the reactants.
Na2SO4(aq)+BaCl2(aq)→BaSO4(s)+2NaCl(aq)
Hence, this is a double decomposition reaction.