Final answer:
The passage from 'To Build a Fire' uses imagery to describe the Yukon River as it paints a vivid picture of the setting without relying on similes, metaphors, onomatopoeia, or alliteration. The correct option is C.
Step-by-step explanation:
The figurative language used to describe the Yukon River in the passage from 'To Build a Fire' leans heavily on imagery. This is evidenced by the vivid descriptions such as the 'dim and little-travelled trail,' the 'subtle gloom that made the day dark,' and the 'unbroken white' landscape. These descriptions engage the reader’s senses and paint a clear picture of the setting.
Similes and metaphors are also forms of figurative language, but they are not specifically highlighted in this passage. Onomatopoeia and alliteration do not seem to be prominent here either. Therefore, the correct answer is C) Imagery, as the language used by the author conjures a strong visual impression of the scene and does not rely on explicit comparisons or sound devices like alliteration or onomatopoeia.