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.