An external examination (also known as an external audit or external review) is the best method for the Chief Information Security Officer (CISO) to gain an understanding of how the company's security policies compare to external regulatory requirements. External examinations are conducted by third-party entities that assess an organization's compliance with laws, regulations, and industry standards. * Penetration tests focus on identifying vulnerabilities, not compliance. * Internal audits assess internal controls but are not impartial or focused on regulatory requirements. * Attestation is a formal declaration but does not involve the actual evaluation of compliance.