The answer is option 3: A technique for making porcelain was perfected.
The art of making porcelain prospered in both periods. A lot of innovations were made in forms, glazes, decorative techniques methods of production and kiln technology.
During the Tang Dynasty, porcelain kilns were constructed all over the country and a type of vessel with molded decorations on it became very popular, which was made using an "upside down" and the coal was used as kiln fuel.
By the Song period, the manufacturing process was standardized (base-making, glazing, ingredient control, and temperature maintenance). In addition, the industry was divided into five types of kilns that had several features for glaze coloring and pattern design.
