Answer:
B. A man's house is his nest.
Step-by-step explanation:
Thoreau's paraphrased metaphor comes from a literal comparison between a man and a bird. In that matter, Thoreau sees a resemblance between the strength a man exhibits when building his own house, and the strength a bird displays when building his own nest. As a result, the metaphor -in which a phrase is applied to something that is not applicable- has to do with a man building his nest.