Why is it often difficult to translate ethical guidelines into practice? Please select all that apply

Why is it often difficult to translate ethical guidelines into practice? Please select all that apply.It is not always possible to inform participants about every aspect of the research.It may not be practical to secure written informed consent with some research methods.Research often has unexpected results and/or undergoes methodological revisions.Some projects are conducted as and when an opportunity arises, involve retrospective data analysis, or otherwise foreshorten the normal process of ethical review.