The FDA has authority to impose clinical holds and terminations on IND studies when subject safety is at risk.

21 CFR 312.44(b)(1): ''The FDA may propose to terminate an IND if it finds that human subjects would be exposed to an unreasonable and significant risk of illness or injury.''

21 CFR 312.42(e): ''If an IND is placed on clinical hold and the deficiencies have not been adequately addressed within 30 days, FDA may terminate the IND.''

Annual reports (A) are required but noncompliance usually results in clinical hold, not immediate termination. IRB approval delays (B) do not trigger termination; the site simply cannot begin. Investigators report safety data to sponsors, not directly to FDA (C).

Thus, the correct answer is D (The FDA issued a clinical hold, and 30 days have elapsed).

21 CFR 312.44(b)(1) (Termination of an IND).

21 CFR 312.42(e) (Clinical hold procedures).