What evidence should a project lead require before approving proposed service boundaries for a modernization effort?

The evidence to require is a documented business-capability and dependency analysis showing why the proposed grouping is cohesive. A stated capability and dependency rationale is what distinguishes a defensible boundary from an arbitrary one, so it is the evidence worth requiring before approval. A count confirming each proposed service contains a similar number of lines is incorrect because equal size says nothing about whether the code inside belongs together. Confirmation that each service shares at least one file with another service is incorrect because shared file access is often incidental, not evidence of cohesion. Sign-off from whichever developer proposed the split is incorrect because a single developer's sign-off does not substitute for an analytical basis. For the exam, require the analysis behind a boundary, not just the boundary itself.