Why Is Ethnography One of the Most Valuable and Distinctive

Why is ethnography one of the most valuable and distinctive tools of the applied anthropologist?

A) It is valuable insider's data that can be routinely sold to multinational corporations and state agencies without the consent of the people studied.
B) It produces a statistically unbiased summary of human responses to set stimuli.
C) It is among the most economical and time-efficient tools that exist in the social sciences.
D) It provides a firsthand account of the day-to-day issues and challenges that the members of a given community face, as well as a sense of how the people think about and react to such issues.
E) It can be produced without leaving the comfort of the anthropologist's office.