What advantage does font substitution provide?

Font substitution is particularly beneficial because it ensures that documents remain viewable regardless of the fonts installed on a user's system. When a document is created with a specific font, that font may not be available on another device. Font substitution allows the document to utilize a default or alternative font that is present on the device, maintaining legibility and readability. This way, content creators can ensure that their work is accessible to a wider audience without being constrained by font availability on different systems.

The other options do not convey the primary advantage of font substitution. Using only one font style would limit design flexibility and is contrary to the purpose of using diverse typography. While aesthetic appeal can be influenced by the choice of fonts, font substitution primarily focuses on accessibility rather than appearance. Document loading speed is typically more affected by factors such as file size or complexity of design elements rather than the fonts used, so this option does not align with the specific benefit of font substitution.