The IRB/IEC is empowered to protect subjects and ensure informed consent remains accurate, complete, and understandable.

ICH E6(R2) 3.1.2:“The IRB/IEC should safeguard the rights, safety, and well-being of all trial subjects. Special attention should be paid… when considering the adequacy and completeness of the written information to be provided to the subjects.”

21 CFR 56.109(b):“The IRB shall require that information given to subjects as part of informed consent is in accordance with §50.25.The IRB may require that information, in addition to that specifically mentioned in §50.25, be given to the subjects when in its judgment the information would meaningfully add to the protection of the rights and welfare of subjects.”

This confirms that the IRB/IEC has unilateral authority to request additional information at any time, regardless of sponsor or investigator agreement.

Thus, the correct answer isA (At any time, at the discretion of the IRB/IEC).