Which of the following scenarios describes a solidary obligation?

A solidary obligation refers to a situation in which each debtor is responsible for the whole obligation, and the creditor can demand the entire performance from any one of the debtors. This means that, in cases where multiple parties are involved, one party can be made to fulfill the obligation entirely, which provides added security for the creditor.

In the context of the other options, while joint ownership without accountability may imply shared responsibilities, it does not capture the essence of a solidary obligation where each party's liability extends to the entire debt. Obligations fulfilled by one party highlights an important aspect of solidary obligations but does not encompass the collective nature of responsibility among multiple parties. Lastly, a contract enforceable by third parties refers to contracts intended to benefit those who are not direct parties to the agreement, which is unrelated to the concept of solidary obligations.