Answer:
A). Submit the research protocol to the IRB for review and submit an IND application to the FDA before conducting the research.
Step-by-step explanation:
As per the question, the most appropriate course of action for the investigator would be to 'Submit the research protocol to the IRB for review and submit an IND application to the FDA before conducting the research.' The investigator would be able to conduct the research only after receiving the necessary permissions as it concerns the lives of young children. Thus, study could be taken forward only after seeking the permission which requires the submission of protocols of the research to IRB and IND application to FDA. Hence, option A is the correct answer.