When creating a 20-page newsletter in which you want different margin settings and other page formats within the multipage document, which one of the following Word features should you use?

A. Styles
B. Formatting
C. Unequal columns
D. Sections

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To create a 20-page newsletter with different margin settings and page formats, you should use the "D. Sections" feature in Word.

Here's how to do it:
1. Open Microsoft Word and create a new document.
2. Click on the "Layout" tab in the top menu.
3. In the "Page Setup" group, click on the "Breaks" dropdown button.
4. Select "Next Page" under the "Section Breaks" section. This will create a new section, indicated by a solid line across the page.
5. Repeat steps 3-4 whenever you want to create a new section with different margin settings or page formats.
6. Click on the "Margins" button in the "Page Setup" group to adjust the margin settings for each section of the newsletter. You can set different margin measurements for each section by selecting "Custom Margins" and adjusting the values accordingly.
7. To change the page format within a section, go to the specific section by clicking at the beginning of a page in that section. Ensure the cursor is at the beginning of the page within the section.
8. Click on the "Layout" tab, go to the "Page Setup" group, and adjust the page format by selecting options like "Orientation" (portrait or landscape), paper size, and columns. These options can be customized for each section.

Using the "Sections" feature, you can have different margin settings and page formats for various parts of your multipage document, such as a newsletter or any other multi-section document.