Which tool is commonly used to create markup language code (e.g., HTML)?

A text editor is the correct choice because it is specifically designed for writing and editing plain text, which is essential for creating markup language code such as HTML. These tools provide features tailored for coding, such as syntax highlighting, line numbering, and sometimes even code completion, which enhances the workflow and makes the process of writing code more efficient and error-free.

Unlike graphic design software, which focuses on visual aspects and layouts rather than code, a text editor is built to facilitate working with textual content. A web browser serves a different purpose, primarily used for rendering and displaying web content, not for creating it. Similarly, a code compiler is used to convert source code written in a programming language into machine code, which doesn't apply to markup languages like HTML that are interpreted rather than compiled. These distinctions highlight why a text editor is the optimal tool for crafting markup language code.