Final answer:
The methodology known as the 'cornerstone' of anthropological fieldwork is Participant observation, which involves researchers immersing themselves in a cultural community for an extended period to gain deep insights.
Step-by-step explanation:
The methodology referred to by the textbook as the "cornerstone" of anthropological fieldwork is B. Participant observation. This qualitative research method is essential in cultural anthropology and involves the researcher spending an extensive amount of time living with, observing, and participating in the activities of a cultural community. The goal is to gain a deep understanding of the knowledge people use to live their lives and how they do so, by making systematic observations that are both accurate and appropriate. Through participant observation, anthropologists can immerse themselves into a new culture and environment, often keeping a daily log of their experiences and reflections.
This research method differs from other forms of participant observation, such as ethnography, in that ethnography focuses on understanding how subjects view themselves about their community rather than testing hypotheses. Participant observation is also a method likely to be used by symbolic interactionists and is a valuable approach when researchers want to explore certain environments from the inside, as it provides an insider's perspective on daily life and social interactions.