Answer:
A) Fog slowly rising from the surface of the pond.
Step-by-step explanation:
Henry David Thoreau wrote his transcendentalist book "Walden" as a reflection of his simple living among nature. He notes in his book how one can only know his true self when he's among nature, away from the automatic and forceful nature of living in the big cities.
From the above provided passage in the question, Thoreau is describing how the fog is slowly rising from the surface of the pond early in the morning. Thoreau is staying in a cabin in the woods, where he survives and lives among nature, away from the monotonous life of cities. He notes that the beauty of nature is fully appreciated when one makes it a necessity to be at one with nature. In the chapter titled "Where I Lived And What I Lived For", he recounts how he was able to notice even the littlest of things, like for instance, this rising of the fog. His use of imagery in describing the scene also makes it more attractive and appealing, instead of just simple putting it in normal simple direct words.