The correct answer is B. External audit.

An external audit provides the strongest assurance of objectivity because it is performed by an independent party outside the organization. A governing body, such as the board or audit committee, relies on independent assurance to determine whether information system controls have been reviewed without management bias or internal influence.

Option A is not the best answer because an administrative audit generally focuses on administrative procedures or operational compliance and does not necessarily provide independent assurance over IS controls. Option C is not the best answer because a forensic audit is usually performed to investigate suspected fraud, misconduct, or evidence-related matters. Option D is valuable, but internal audit is still part of the organization; therefore, an external audit generally provides stronger objective assurance to the governing body.

This maps to Information Systems Auditing Process , because ISACA’s CISA Exam Content Outline includes IS audit standards, audit execution, evidence, reporting, and assurance activities under Domain 1. ( ISACA )