What must the investigator obtain to ensure compliance with ICH guidelines?

The correct answer emphasizes the necessity for an investigator to obtain a confirmation from the Institutional Review Board (IRB) that ensures compliance with ICH guidelines. This step is crucial because the IRB plays a vital role in protecting the rights and welfare of research participants. By obtaining this statement, the investigator confirms that the study protocol has undergone a thorough ethical review, ensuring that it meets the safety and ethical standards established by the ICH guidelines.

This aspect of compliance is essential as it ensures that all human subject research adheres to ethical principles, promoting participant safety and the integrity of the study results. Adherence to established guidelines is particularly important in maintaining public trust in clinical research practices.

The other options may seem relevant but do not directly signify compliance with ICH guidelines. For instance, obtaining signed statements from subjects might focus on informed consent, and while it is critical, it is not specifically tied to ensuring compliance with ICH as a whole. A statement from the sponsor may verify some aspects of the trial, but it does not carry the ethical oversight that an IRB provides. Similarly, a report on previous trial results, while useful for understanding context and potentially informing future research, does not relate directly to compliance with ICH standards.