Stage 1 is the readiness and preliminary assessment stage of an initial certification audit. Its purposes include reviewing relevant management-system documented information, assessing site-specific conditions and determining whether the organisation is sufficiently prepared for Stage 2. Any weaknesses that could become nonconformities during Stage 2 can therefore be communicated as areas of concern, making C correct. Option A is incorrect because ISO 19011 provides auditing guidance; the formal two-stage certification requirements are established through ISO/IEC 17021-1. Option B describes the more extensive Stage 2 assessment, where effective implementation and conformity are evaluated. Option D is also incorrect because discussions with client personnel form part of Stage 1 readiness determination. ISO 45001 Lead Auditor training material explicitly identifies Stage 1 areas of concern that could become Stage 2 nonconformities.