Which of the following is an effective mannerism on the part of the instructor?

Gesturing is an effective mannerism for an instructor because it enhances communication by helping to convey emotions and emphasize key points. Proper gesturing can direct the audience's attention and aid in the retention of information being presented. It also helps in making the instructor appear more engaging and approachable, fostering an interactive environment during educational sessions.

In contrast, other options may not serve the same purpose effectively. For instance, foot tapping or jingling coins or keys can be distracting; they may divert the audience's focus away from the content being delivered. Additionally, finger snapping, while it might capture attention, can come across as informal or unprofessional depending on the context, which might undermine the instructor's authority and the seriousness of the material being taught. Therefore, gesturing stands out as a positive mannerism that supports effective teaching and enhances the learning experience.