According to the PMBOK Guide, when using an agile approach, the project manager needs to have a clear understanding of the product vision, the product roadmap, and the product backlog1. The product vision is a brief statement that describes the desired outcome of the project and the value it will deliver to the customers and stakeholders2. The product roadmap is a high-level overview of the product features and deliverables, along with the planned timeline and milestones3. The product backlog is a prioritized list of the product requirements, user stories, and other work items that need to be completed by the project team. These three factors help the project manager to align the project objectives with the customer needs, plan and execute the project iteratively and incrementally, and deliver value early and often1. The other options are not relevant for an agile approach, as they are more suitable for a predictive or waterfall approach. Key performance indicators (KPIs) are metrics that measure the performance of the project against the project objectives. Schedule performance index (SPI) is a ratio of the earned value to the planned value, indicating how well the project is progressing according to the schedule. These factors are not essential for delivering a product using an agile approach, as they focus more on the adherence to the plan rather than the delivery of value. References:

1: PMBOK Guide, 6th edition, page 18

2: PMBOK Guide, 6th edition, page 156

3: PMBOK Guide, 6th edition, page 157

: PMBOK Guide, 6th edition, page 158

: PMBOK Guide, 6th edition, page 33

: PMBOK Guide, 6th edition, page 267