Which of the following is a guideline for using headings in content outlines?
All headings of the same level should be treated consistently.
Different font styles and colors should be used for headings of the same level.
First-level headings should contain only one second-level heading.
All first-level, second-level, and third-level heading should be numbered using Roman numerals.
The correct guideline for using headings in content outlines is:
All headings of the same level should be treated consistently.
This means that headings at the same level should have the same formatting, style, and structure to maintain clarity and organization in the outline. The other options provided do not represent standard guidelines for headings in content outlines.