Which of the following features should you use when typing in the notes text box?

Answer: Option A

When typing in the notes text box in PowerPoint, you should use the Slide show feature. This allows you to view your presentation in full-screen mode, where notes you've entered can be displayed separately for the presenter.
Insert is used to add various elements such as images, charts, or shapes to slides.
Slide master is used to make global design changes to slides, such as fonts, backgrounds, and placeholders.
Zoom is used to navigate through different sections of a presentation in a non-linear way.
Therefore, the correct answer in this context is Option A: Slide show.