Explanation
One of the key principles of agile project management is to deliver value to the customer frequently and iteratively. This means that the team should aim to deliver working software or features that meet the customer's needs and expectations in each iteration, rather than waiting until the end of the project to deliver the whole product. This way, the team can get feedback from the customer and make adjustments as needed, as well as reduce the risk of delivering something that does not satisfy the customer. Therefore, if the team discovers that they are unable to implement a feature completely in the first iteration, and that the feature is a critical component that the customer has prioritized, the best option is to split the feature into smaller subfeatures, implement them, and then deliver them incrementally in multiple iterations. This will allow the team to deliver value to the customer sooner, as well as to manage the scope and complexity of the feature more effectively. The other options are not consistent with the agile principles and values, as they may compromise the quality, functionality, or customer satisfaction of the feature. Reducing the scope of the feature to fit into one iteration may result in delivering a feature that does not meet the customer's requirements or expectations, or that is not fully tested or integrated. Going back to the customer and explaining that they cannot implement the feature completely in one iteration may cause the customer to lose trust or confidence in the team's ability or commitment, or to perceive the team as inflexible or unresponsive.
Asking the customer to simplify the feature so that it can be implemented in one iteration may imply that the team is not willing or able to handle the complexity or challenge of the feature, or that the team is not respecting the customer's needs or preferences. References:
PMI, A Guide to the Project Management Body of Knowledge (PMBOK Guide) - Sixth Edition, Project Management Institute Inc., 2017, pp. 28-29, 35-36, 54-55.
Agile project management and the PMBOK guide, Sliger, M. (2008). Agile project management and the PMBOK guide. Paper presented at PMI Global Congress 2008-North America, Denver, CO.
Newtown Square, PA: Project Management Institute.
What Is Agile Project Management?, Good, L. (2023). What Is Agile Project Management?
Project-Management.com.