B. Simile
The literary device most prominent in this excerpt from Frost's poem "Mending Wall" is B. Simile.
A simile is a figure of speech that directly compares two different things, often using the words "like" or "as" to make the comparison. In this excerpt, Frost uses the simile "And some are loaves and some so nearly balls" to compare the shape and size of the boulders they are working with to bread loaves and balls. He is creating a vivid image of the varying sizes and shapes of the stones, which must be carefully balanced in order to construct the wall.
~~~Harsha~~~