Final answer:
Evidence that supports the struggle of the man against the extreme cold in the Yukon in 'To Build a Fire' is found in the detailed descriptions of the freezing temperatures and the differing reactions of the man and his dog, underlining the theme of man versus nature.
Step-by-step explanation:
The subject of the student's question pertains to the examination of textual evidence within a literary context, specifically related to the story 'To Build a Fire' by Jack London, as well as other literary works that are mentioned. A piece of evidence that supports the harshness of the Yukon and the struggle between the man and the environment is the detailed description of the cold, showcasing how the man is not as aware of the severe conditions as his dog, who, through instinct, understands the danger of the cold much better. In the excerpt, London writes about the man's surprise at the severity of the cold and his efforts to warm up, as well as the dog's instinctual hesitation to continue traveling in such extreme temperatures. These examples highlight the central conflict of man versus nature, a common theme in naturalist literature, and serve as strong evidence for the question concerning the character's struggles.