Which comparison from walden conveys thoreau’s belief that people do not have to conform to what everyone around them is doing?

a.
if a man does not keep pace with his companions, perhaps it is because he hears a different drummer.

b.
still we live meanly, like ants.

c.
like pygmies we fight with cranes.

d.
in the midst of this chopping sea of civilized life, such are the clouds and storms and quicksands.