The following text is from Frances Burney's 1784 satirical play The Busy Salon. Clara, Lady Venom, and Edward Fairman are discussing their mutual acquaintance Lord Arthur Sharp.
CLARA: [Lord Arthur] has done nothing—but his talk is a perpetual slander on all his acquaintances.
FAIRMAN: Aye, and the worst of it is there is no advantage in not knowing him, for he'll abuse a stranger just as soon as his closest friend—and [his cousin] is as bad.
LADY VENOM: Nay, but we should make allowance. Lord Arthur is a wit and a poet.
CLARA: For my part—I admit, madam—wit loses its respect with me when I see it in company with malice. What say you, Mr. Fairman?
FAIRMAN: Certainly, madam, to smile at the jest that leaves a wound in another's heart is to become a principal in the mischief.
Which choice best describes the function of the underlined sentence in the text as a whole?