Which of the following describes a style guide?

A style guide is indeed a document that specifies layout and visual elements, serving as a framework for maintaining consistency in various types of written and visual communications. It typically includes rules regarding typography, color schemes, spacing, and formatting, which all contribute to a unified brand identity and ensure that all materials adhere to predefined standards. This consistency is essential for fostering recognition and professionalism across different platforms and publications.

While the other options might touch on aspects of design or branding, they do not encapsulate the broader purpose of a style guide. For instance, a digital watermark pertains more to copyright protection rather than layout specifics, and website-safe fonts focus on digital accessibility rather than the comprehensive overview provided by a style guide. Similarly, securing trademarks relates to legal protections instead of outlining stylistic elements. Therefore, option A accurately reflects the comprehensive and foundational role a style guide plays in document production.