Which sentence in this excerpt from herman melville's "bartleby, the scrivener" best exhibits the use of verbal irony?

ginger nut, the third on my list, was a lad some twelve years old. his father was a carman, ambitious of seeing his son on the bench instead of a cart before he died. so he sent him to my office, as student at law, errand boy, cleaner and sweeper, at the rate of one dollar a week. he had a little desk to himself, but he did not use it much. 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.

. . for the first time in my life a feeling of overpowering stinging melancholy seized me. before, i had never experienced aught but a not unpleasing sadness. the bond of a common humanity now drew me irresistibly to gloom.

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.