The objective of an internal audit engagement is to evaluate the organization's ethics program.

Comprehensive and Detailed Explanation:

An effective ethics program requires clear policies, communication, monitoring, and investigation procedures. To evaluate its adequacy, the auditor should examine established investigation protocols (B) — i.e., how allegations of misconduct are handled, investigated, and resolved. The strategic plan (A) is high-level and does not directly address ethics processes. The overall budget (C) is too broad, and officer remuneration (D) is not core evidence of program quality. According to IIA guidance, assessing the ethics program involves verifying that mechanisms exist for reporting, investigating, and addressing ethical issues. Therefore, the most relevant scope element is Option B.