D all of the above, I'm in apex too
The value of the water is it has minerals in it to make it so valuable but also it's all they have.<span />
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.
<span>Several forms of kitchen wares like pots, pans, jugs, etc. can be turned into fossils when preserved under right conditions. These relics/artifacts are actually a good tool or link as to how people lived their daily lives back then. They also give a glimpse of the several practices/traditions that people do within different kinds of cultures.</span>