Which characteristic distinguishes a markup language from other languages?

A markup language, such as HTML or XML, is fundamentally different from a programming language. Its primary purpose is not to execute algorithms or perform logic but to annotate a document, defining the structure, layout, and meaning of its content. It uses tags to describe elements like headings, paragraphs, and images, rather than to declare variables or control program flow.

A. Decomposing programs into custom types is a feature of object-oriented programming languages like Java or C++, not markup languages.

B. Allowing variables to change type during execution is a characteristic of dynamically-typed programming languages like Python or JavaScript.

C. This statement also describes a feature of dynamically-typed programming languages, which is irrelevant to markup languages that lack variables and type systems.

1. MDN Web Docs. (2023). Getting started with HTML. "HTML (HyperText Markup Language) is not a programming language; it is a markup language used to tell your browser how to structure the webpages you visit."

2. World Wide Web Consortium (W3C). (2018). HTML 5.2, W3C Recommendation, Section 1.1. "HTML is the World Wide Web's core markup language." The document describes its role in structuring documents for the web.