Answer:
In this excerpt from the story, the tone of the shop girl's is insincere.
Step-by-step explanation:
When we read the whole excerpt, it becomes evident that the tone is insincere. The girl knows that, if she pays the compliments in an intelligent manner, she will sell the gloves. The client will feel not only flattered but also obliged to pay for the gloves, even if they don't fit. That is precisely what happens. The speaker, however, notices the girl's true purpose when the purchase is already completed:
I detected a light in the woman's eye that was gently ironical, and when I looked back from the street, and she was laughing to herself about something or other, I said to myself, with withering sarcasm: "Oh, certainly; you know how to put on kid gloves, don't you?—a self-complacent heel, ready to be flattered out of your senses by every petticoat that chooses to take the trouble to do it!"