Which of the following contracts may reflect obligations to be performed over time?

The concept of obligations being performed over time is most closely associated with an installment contract. An installment contract is structured to allow for the delivery of goods or services in multiple parts or stages, along with corresponding payments occurring at set intervals. This format inherently establishes a timeline for both the performance of obligations and payment, thereby allowing for a clear understanding of when each component of the contract must be fulfilled.

In contrast, fixed contracts typically demand performance at a single point in time, with obligations completed in one go, which does not support a gradual or time-phased approach. Revolving contracts may involve ongoing transactions or supply arrangements but are generally associated with credit or financing mechanisms and do not imply a specific performance timeline like an installment contract does. The all or none contract concept entails that the entire agreement must be fulfilled in its entirety or not at all, lacking the phased obligations that characterize an installment arrangement. Hence, installment contracts stand out as those that explicitly reflect obligations to be performed over time.