Final answer:
The 1572 form, also known as the Statement of Investigator, is required when submitting an IND application to the FDA for approval. It does not need to be submitted to the FDA regularly, but only when requested by the sponsor.
Step-by-step explanation:
The 1572 form, also known as the Statement of Investigator, is a document that provides a commitment from the investigator to the US Food and Drug Administration (FDA) to comply with the regulations related to clinical trials. The use of the 1572 form is required when submitting an Investigational New Drug (IND) application to the FDA for approval.
Therefore, the answer to the question is D) Only if requested by the sponsor. The 1572 form does not need to be submitted to the FDA on a regular basis like weekly or annually, but rather, it needs to be submitted only when requested by the sponsor.