Open the rejection in Resolution Center and click "reply" not "resubmit". Ask for the specific guideline number (e.g., 4.0, 5.1.1) and the specific screen they're flagging. Reviewers respond to direct questions. Don't just resubmit hoping a different reviewer will pass it, same reviewer often picks it up again.
Prompt to paste
Apple rejected my app with this vague reason: [paste rejection]. Draft a polite Resolution Center reply that asks for the specific guideline number and the exact screen they're flagging, and asks what change would resolve it. Keep it short and direct so a reviewer will actually answer.