Which term describes a group of connected sentences covering one main topic in a work of prose?

The term that describes a group of connected sentences covering one main topic in a work of prose is "paragraph." A paragraph is a fundamental building block of written communication, organizing thoughts and conveying a unified idea or theme. In prose, each paragraph typically begins with a topic sentence that introduces the main idea, followed by supporting sentences that elaborate on that idea, providing detail, examples, and further explanation.

In contrast, "stanza" refers to a grouped set of lines in poetry, which is not applicable to prose. "Dialogue" denotes the spoken exchanges between characters in a narrative, often found within paragraphs but not defining their structure. "Couplets" specifically refers to two lines of poetry that rhyme and have the same meter, making it irrelevant in the context of prose. Thus, "paragraph" is the correct choice as it accurately describes the structural element that organizes ideas in prose writing.