Examine the use of rhetorical devices in the passage below. The millions are awake enough for physical labor; but only one in a million is awake enough for effective intellectual exertion, only one in a hundred millions to a poetic or divine life. To be awake is to be alive. I have never yet met a man who was quite awake. How could I have looked him in the face?

What is the point of the rhetorical question in this passage?
a to express Thoreau's annoyance at sleepy, unproductive people to tell us that
b Thoreau is afraid of looking others in the eye
c to suggest that being fully awake is an extraordinary thing
d to create a comical effect by describing something impossible