Which of the following best describes commodities?

The definition of commodities primarily refers to raw materials or primary agricultural products that can be bought and sold. This encompasses a wide range of goods that are often standardized and traded on various markets. Examples include grains, oil, gold, and other natural resources that are produced in bulk and can be interchanged with other goods of the same type. By this understanding, option B accurately identifies that commodities include agricultural and mining products that are traded.

In contrast, refined products, financial assets, and luxury items do not fall under the traditional definition of commodities. Refined products are a step beyond raw materials and are typically the result of processing commodities, thus not representing the initial tradeable goods themselves. Financial assets are investment vehicles that represent ownership in companies or debt but do not comprise physical goods like commodities. Luxury items, while they may hold significant market value, typically entail branding and exclusivity rather than the broad market interchangeability characteristic of commodities. Therefore, the most fitting description among the provided choices is that which emphasizes the agricultural and mining aspects of commodities.