Final answer:
The 'complete participant' role in sociological research involves fully immersing oneself in the group being observed. While it provides access to authentic behaviors, it can raise ethical concerns due to potential influence on others. All observer roles in sociological research have ethical considerations.
Step-by-step explanation:
The variety of observer roles in sociological research includes the 'complete participant' role, among others. The 'complete participant' refers to a researcher who fully immerses themselves in the group being observed, participating in their activities and blending in seamlessly. While the 'complete participant' role may have advantages in terms of gaining access to authentic behaviors, it can also raise ethical concerns. By actively engaging and participating in the group, the researcher may influence or affect the behavior of others, potentially compromising the research objectivity and informed consent of participants. However, it is important to note that all observer roles in sociological research have their potential ethical considerations.