Which sentence in this excerpt from Herman Melville's "Bartleby, the Scrivener" best exhibits the use of verbal irony?

a. Before, I had never experienced aught but a not unpleasing sadness.

b. Upon inspection, the drawer exhibited a great array of the shells of various sorts of nuts. Indeed, to this quick-witted youth, the whole noble science of the law was contained in a nutshell.

c. So he sent him to my office, as student at law, errand boy, cleaner and sweeper, at the rate of one dollar a week.

d. For the first time in my life a feeling of overpowering stinging melancholy seized me.