In the United States, following the ICH E6 guideline is:

In the United States, following the ICH E6 guideline is:

1: Voluntary for FDA-regulated drug studies.

2: Mandatory for studies conducted outside the United States.

3: Mandatory for investigational device studies.

4: Mandatory for drug studies.

Answer: 4: Mandatory for drug studies.

The International Council for Harmonisation (ICH) E6 guideline, otherwise recognized as the Good Clinical Practice (GCP) guideline, is a standard worldwide ethical and scientific quality practice established for conceptualizing, organizing, documenting, and disclosing clinical studies (trials) involving human participants. In the United States, (studies) as per the ICH E6 are a compulsory requirement for the FDA, which is an institution that regulates drugs. The guidelines of this study includes safeguarding of subjects of humanity, and e., the pulling down of data which are not of the drugs .