The correct answer is: A. Stone ware pipes.
Lead caulked joints are used for laying stone ware pipes because they are a durable and watertight joint. Lead is a soft metal that can be easily shaped and molded, making it ideal for this type of joint. It is also a good conductor of heat, which helps to prevent the pipes from freezing in cold weather.
Earthenware pipes are made of clay and are not as durable as stone ware pipes. They are also more porous, which means that they can leak more easily. C.I. pipes are made of cast iron and are very strong, but they are also very heavy. G.I. pipes are made of galvanized steel and are lightweight, but they are not as strong as C.I. pipes.
In conclusion, lead caulked joints are used for laying stone ware pipes because they are a durable and watertight joint.