Answer: C, markup language (such as HTML, XML)
Answer analysis:
When discussing which language uses special symbols called "tags", we must first clarify the meaning of the term "tag" in different fields and contexts. Generally speaking, in programming, markup languages (such as HTML, XML), and certain specific fields (such as database query languages), "tags" are special strings or symbols used to define data or code blocks.
Now, let's analyze several possible languages or technologies one by one:
A. Natural languages (such as English, Chinese, French, etc.): These languages are mainly used for communication between humans, and they do not use special symbols called "tags" to define data or code blocks. Sentences, paragraphs, etc. in natural languages are organized and understood through grammar, vocabulary, and context, not through tags.
B. Programming languages (such as C, Java, Python, etc.): Although these languages have specific grammatical rules and symbols, they mainly use keywords, variable names, operators, etc. to write programs, and do not directly use "tags" as core elements. However, in template engines or certain specific programming practices, tag-like structures may be used to embed code or data.
C. Markup languages (such as HTML, XML): These languages explicitly use tags to define the structure and content of data. For example, in HTML, the `<p>` tag is used to define a paragraph, and the `<a>` tag is used to define a hyperlink. These tags are special symbols that define the structure and content of a document, which fully conforms to the description of "special symbols called tags" in the question.
D. Database query languages (such as SQL): Although SQL is used to query and operate databases, it mainly uses statements (such as SELECT, INSERT, UPDATE, etc.) and specific syntax rules, and does not directly use "tags" as core elements to define data or operations.
In summary, C. Markup languages (such as HTML, XML) explicitly use special symbols called "tags" to define and organize data. These tags not only define the structure of the data, but also allow the document to be styled and dynamically interacted through style sheets (such as CSS) and scripts (such as JavaScript).
Therefore, the answer is C. Markup languages (such as HTML, XML) use special symbols called tags.