A stakeholder says an assumption was validated eighteen months ago so there is no need to revisit it. What is the correct response?

• AThey are right, since re-running validation duplicates work already done.
• BValidation results should be re-checked on a fixed annual schedule regardless of context.
• COnly quantitative evidence expires, so qualitative findings remain valid indefinitely.
• DEvidence has a shelf life. Markets, competitors and users all move, which is why the loop repeats rather than closing, and eighteen month old evidence is a hypothesis again.