The correct answer is B. Location
Explanation:
In narratives, the setting refers to the context or circumstances in which the story takes place. This includes the location that refers to the specific geographical place and the conditions of the place such as weather, relief, etc. This aspect of the setting is emphasized in the excerpt from A Princess of Mars because the narrative mentions the weather conditions in Mars "the Martian nights are extremely cold...changes in temperature are sudden and most uncomfortable", which allow the reader to know the specific place where the story is (Mars) and the weather conditions in it.