Which of the following best describes a distinct section of writing?

The option that best describes a distinct section of writing is a paragraph. A paragraph is a grouping of sentences that focus on a single main idea or topic. It typically includes a topic sentence that introduces that idea, along with supporting sentences that provide additional details or explanations. Paragraphs are fundamental components of writing, serving to organize thoughts and enhance clarity in communication.

In contrast, a title serves as a label or heading for a work but does not constitute a section of writing itself. A bookmark is used for marking a specific place in a text and is not part of the writing. A bibliography is a list of sources used in the research or referenced in a work, but it again does not represent a section of written content in the same way a paragraph does. Thus, among the provided options, a paragraph distinctly represents a well-defined section of writing.