A penetration test is normally the only security assessment that can link vulnerabilities together by exploiting them sequentially. This gives a good measurement and prioritization of risks. Other security assessments such as vulnerability scans, code reviews and security audits can help give an extensive and thorough risk and vulnerability overview', but will not be able to test or demonstrate the final consequence of having several vulnerabilities linked together. Penetration testing can give risk a new perspective and prioritize based on the end result of a sequence of security problems.

Explanation
The document that should include contact information for representatives of equipment and software vendors is the business continuity plan (BCP) because it provides the guidance and procedures for restoring the organization's critical business functions and operations in the event of a disruption or disaster, and may require contacting external parties such as vendors for assistance or support. Information security program charter is not a good document for this purpose because it does not provide any guidance or procedures for business continuity or disaster recovery. Business impact analysis (BIA) is not a good document for this purpose because it does not provide any guidance or procedures for business continuity or disaster recovery.
Service level agreements (SLAs) are not good documents for this purpose because they do not provide any guidance or procedures for business continuity or disaster recovery. References:
https://www.isaca.org/resources/isaca-journal/issues/2017/volume-2/business-continuity-management-lifecycle
https://www.isaca.org/resources/isaca-journal/issues/2016/volume-4/business-impact-analysis