Final answer:
The styles displayed by default in the Style gallery and Styles pane are called Current theme styles, which are part of the applied theme in word processing programs.
Step-by-step explanation:
The styles that are displayed in the Style gallery and Styles pane by default are known as D) Current theme styles. These styles are a set of formatting choices that are designed to be used together to give your document a cohesive and professional appearance. They are part of the current theme applied to a document in word processing programs like Microsoft Word. A theme typically includes a set of colors, fonts, and effects that are applied to elements such as headings, titles, and body text.