Explanation:

- The French ethnologist and sociologist known for essays on the Eskimo, religious rituals, the significance of gifts, and the sociology-psychology relationship is Marcel Mauss.

- Émile Durkheim was a pioneering sociologist focused on social facts, anomie, and the collective conscience, but not specifically known for essays on gifts or Eskimo studies.

- Auguste Comte is credited as the father of positivism and sociology, but didn’t write about gift exchange or Inuit populations.

- Saint Simon was an early social theorist but not involved in ethnographic or gift-related studies.