What best describes a 'design specification'?

A design specification is fundamentally a comprehensive and detailed outline of the requirements and criteria that a product must fulfill in order to be considered successful. It serves as a foundational document that guides designers throughout the development process, ensuring that all necessary aspects of the design, such as functionality, aesthetics, and usability, are considered and met.

The strength of the design specification lies in its ability to clarify and communicate the objectives of a project, helping to define the scope and expectations. It typically includes specific features, dimensions, performance standards, and any other relevant parameters that the final product must adhere to, aligning with user needs and market demands.

Other options, while potentially relevant in different contexts, do not encapsulate the essence of what a design specification entails. For instance, budget and timeline are important for project management but do not address the specifics of the product design itself. Similarly, listing materials may inform part of the design process, yet it doesn't encompass the broader criteria and performance requirements established by the design specification. Marketing guidelines focus on how to present and sell the product rather than its design functionalities. Thus, the most accurate description here is indeed that of a detailed description of the criteria a design must meet to be successful.