In which of the following scenarios would you use a hyphen?

Using a hyphen to separate a prefix from a proper noun is correct because it clarifies the relationship between the two parts and prevents confusion. For instance, in phrases such as "un-American,” the hyphen is essential for indicating that "un" modifies "American" rather than creating a new word with a different meaning.

Hyphens are commonly employed in such instances as they help maintain clarity in writing, especially with prefixes like "un-", "non-", and "anti-" when they precede proper nouns. This practice is important in ensuring that the reader understands the intended meaning without ambiguity.

While there are other situations where hyphens are applicable, such as in connecting compound adjectives or in specific number formats, these do not align with the scenario provided. Thus, the use of a hyphen in conjunction with a prefix and a proper noun stands out as a rule of grammar essential for maintaining clarity and precision in writing.