Which of the following conjunctions functions to join two alternatives?

The conjunction that functions to join two alternatives is "either-or." This pair of words is specifically designed to present a choice between two options, indicating that one of them will be selected or is true while the other is not.

For example, in the sentence "You can either have coffee or tea," "either-or" clearly delineates the two alternatives being presented to the reader or listener. This makes it quite effective in decisions or situations where a choice must be made.

In contrast, the other conjunctions mentioned do not serve the same purpose. "But" introduces contrast, suggesting a shift from one idea to another rather than presenting alternatives. "Both-and" indicates inclusion rather than choice, and "yet" usually adds a contrasting element to what has been stated previously. Understanding the specific function of these conjunctions helps clarify their roles in sentence structure and meaning.