What type of contract involves goods that have a 'valuable interest'?

The correct answer is related to the nature of the goods involved in the contract. A commodity contract specifically pertains to goods that are typically seen as interchangeable, meaning they have intrinsic value and can be traded. This type of contract revolves around commodities like oil, gold, wheat, and other raw materials that are traded in bulk. The "valuable interest" in this context refers to the economic significance and market value associated with these goods.

Commodity contracts are inherently distinct from service contracts, which involve the provision of services rather than tangible goods. Similarly, divisible contracts and installment contracts relate to different aspects of fulfillment and payment structures rather than the intrinsic value of the goods themselves. Therefore, understanding that a commodity contract is inherently tied to the value and trade of physical goods clarifies why this is the correct choice.