The correct option is (a) True
To explain: Better surface finish of castings with close tolerances are produced by Co2 moulding, but it is still not economical than the green sand moulding because this process uses expensive devices like Co2 cylinder, hoses, regulator, hand held applicator gun or nozzle etc., and the processes in green sand moulding are simple and no expensive devices are required, due to this, green sand moulding is more economical.