Final answer:
To apply color behind text with adjustable margins, the correct option is paragraph shading. This feature provides control over the color area specifically around the text, unlike background color or text fill.
Step-by-step explanation:
When you want to apply color behind paragraph text and also have the ability to adjust color margins, you use paragraph shading. Neither background color nor text fill provide the option to adjust margins specifically around the text. And border color deals with the color of the border around the text box, paragraph or page, not the shading behind the text itself.
Paragraph shading is particularly useful in document styling and formatting as it allows you to highlight text or differentiate sections of a document. It also gives you control over how much space the shading occupies, which can enhance readability or serve a specific design purpose.