On an agile project in a changing business environment, the sponsor is concerned about benefits realization and asks the project manager to monitor changes that could affect the product. What should the project manager do to identify changes that may affect the product?

Reprioritizing the backlog after each iteration is the most effective way to identify and respond to changes affecting the product's value. This ensures that the team is always working on the highest-value items, directly addressing the sponsor's concern about benefits realization in a changing environment. Face-to-face communication is valuable but doesn't explicitly address identifying changes to product value. Stopping an iteration immediately is an extreme measure and not a proactive strategy for monitoring changes. While pair programming improves code quality and responsiveness, it doesn't directly address the strategic identification of changes impacting overall product relevance or business value.