Final answer:
The FDA can halt gene therapy development at any stage, including upon IND submission, during clinical trials, or post-approval during production and marketing. Hence, all provided options are correct.
Step-by-step explanation:
A sponsor must submit the Investigational New Drug (IND) application to the FDA's Center for Drug Evaluation and Research (CDER) after collecting adequate laboratory data, including animal trial results. Upon submission, there is a 30-day waiting period for the FDA to review the IND before clinical trials involving human subjects can commence. The FDA has the authority to place a clinical hold at multiple stages: upon submission of an IND, during clinical trials, and even after the therapy is approved, during manufacturing and marketing, if any issues regarding safety or protocol compliance arise.
Therefore, the answer to the multiple-choice question is d): all of the answers are correct. The FDA can halt the development or use of gene therapy at any stage if there are significant concerns that need to be addressed.