Ethnography is the detailed account of a society and its culture by observing the social interactions that people have. This gives us an accurate description of a society and its culture as it not influenced by outside factors.
Here, Maria is studying the the lives of women in coffee farming communities in Brazil. She is observing them directly and making sure her presence does not influence their interactions. She is also doing this herself which means her research will not be affected by someone else's perspective.
Hence, she is using the strategy of first-hand ethnographic fieldwork.
This is of course subjective, but in general, compromise if often wise
in political situations in which people share resources. It is not wise when violations of basic human rights are involved.