Performance requirements established by the buyer before engagement is correct because vendor prequalification should be based on the buyer defining what is required up front.

When the buyer sets Performance requirements established by the buyer before engagement those requirements translate into measurable criteria such as service levels security controls delivery timelines and quality metrics that enable objective comparison and selection of suppliers.

Previous project performance records are useful as supporting evidence but they are retrospective and may not match the buyer's specific needs or current context so they should not be the primary prequalification basis.

Capability maturity framework can indicate process maturity and organizational discipline but it does not guarantee that a vendor will meet the specific performance requirements of a contract and it may overlook project level capabilities.

Assessment of supplier competency through examinations can validate knowledge or certifications but examinations do not prove real world delivery performance or the ability to meet contractual obligations under the buyer's conditions so they are insufficient on their own.

Full AWS Practitioner Certification Question