Which of the following determines the colors initially available to you when applying shading to a new document?

The current theme determines the colors that are initially available for shading in a new document. A theme in Word is a predefined set of formatting options that includes colors, fonts, and effects. When a new document is created, it adopts the default theme, which specifies the color palette that can be used for various elements, including shading. This ensures consistency and coherence in the document’s appearance.

While user settings may allow customization of features and preferences within Word, they do not directly dictate the initial color options available for shading. Similarly, document type mainly influences formatting and layout options rather than color choices. Lastly, font style relates to the text's appearance rather than the available color palette for shading elements in the document. Therefore, the current theme is the correct determinant for the available shading colors.