Answer:
b) To indicate that the boulders are different shapes and sizes.
Step-by-step explanation:
In these lines of Mending Wall by Robert Frost, the author uses these descriptions in order to indicate that the boulders were all of different shapes and sizes. He tells us that some of the boulders were loaves, which implies a longer shape. Some others were nearly balls, which implies that they more closely resembled spheres. The fact that they are all different shapes and sizes means that it was very difficult to balance them.