The correct answer is A. patter.
Patter is a rapid, continuous flow of speech, especially of a light or trivial nature. It is often used in sales and marketing to persuade customers to buy a product or service.
Chatter is a less formal term for patter, and it can also refer to the act of talking in a light-hearted or frivolous way.
Tapping is the act of making repeated light blows with the fingers or a light object, such as a pencil. It can be used as a form of communication, as a way to attract attention, or as a way to express oneself.
Jabber is rapid, unintelligible speech. It is often used to describe the speech of someone who is very excited or agitated.
In the context of the question, the sales girl’s glib patter helped her a lot in her profession because it allowed her to engage with customers in a friendly and persuasive way. Her patter was also likely well-rehearsed and tailored to her target audience, which made it even more effective.