At the end of the nineteenth century, a rising interest in Native American customs and an increasing desire to understand Native American culture prompted ethnologists to begin recording the life stories of Native American. Ethnologists had a distinct reason for wanting to hear the stories: they were after linguistic or anthropological data that would supplement their own field observations, and they believed that the personal stories, even of a single individual, could increase their understanding of the cultures that they had been observing from without (from without: 从...外面). In addition many ethnologists at the turn of the century believed that Native American manners and customs were rapidly disappearing, and that it was important to preserve for posterity as much information as could be adequately recorded before the cultures disappeared forever.
请问红字加粗的部分,怎么理解呢? 有一道题的答案就是根据这句话推出来的,但我还不明白 6. It can be inferred from the passage that a characteristic of the ethnological research on Native Americans conducted during the nineteenth century was the use of which of the following?
A. Investigators familiar with the culture under study. B. A language other than the informant's for recording life stories C. Life stories as the ethnologist's primary source of information D. Complete transcriptions of informants' descriptions of tribal beliefs E. Strigent guidelines for the perservation of cultural data