What method involves immersing oneself into a culture to study it from within?

The correct answer is ethnography, which is a qualitative research method primarily used in the field of anthropology. Ethnography involves the immersive study of people and cultures by researchers who engage directly with the communities they are studying. This approach allows researchers to gain insights into people's lives, beliefs, practices, and social interactions from an insider's perspective. By participating in the daily activities of a culture and observing behaviors in natural settings, ethnographers can gather rich, detailed data that goes beyond what might be gleaned from surveys or other more detached methods.

Anthropology, while related, is the broader field that encompasses various methods, including ethnography, but does not specifically highlight the immersive aspect. Survey research focuses on collecting data through questionnaires or interviews and is less about immersion in a culture. Case studies, on the other hand, generally involve an in-depth analysis of a single event, group, or situation rather than the extensive immersion characteristic of ethnographic studies. Thus, ethnography stands out as the method that specifically emphasizes cultural immersion for the purpose of study.