Which type of clay is fired at temperatures of less than 1200 degrees Celsius?

Earthenware is the correct answer as it is fired at lower temperatures, typically below 1200 degrees Celsius. This type of clay is characterized by its porous nature and is often used for pottery and ceramic items that do not require high firing temperatures. The firing process for earthenware creates pieces that retain some moisture and can absorb water, which is why they are often glazed for practical use.

Stoneware, on the other hand, is fired at higher temperatures, usually between 1200 and 1300 degrees Celsius, making it denser and more durable than earthenware. Porcelain requires even higher firing temperatures, generally above 1200 degrees Celsius, resulting in a very fine and translucent ceramic. Kaolin, while a type of clay, is primary clay from which porcelain is made and is also fired at high temperatures. Therefore, the characteristics and firing temperatures of these materials emphasize why earthenware is the suitable choice for this question.