Which sentence uses a hyphen in a compound modifier correctly?

• A. She is a well known author.
• B. She is a well-known author.
• C. She is well-known author.
• D. She is a well known-author.

Answer: (B)

When a compound modifier comes directly before a noun, it should be joined with a hyphen so the words form one describing unit. Here, well-known describes the noun author as a single idea, so the hyphen makes the meaning clear: a well-known author. Without the hyphen, well known reads as two separate adjectives, which isn’t the standard way to style a modifier before a noun. Placing the hyphen after well in well-known-author creates an incorrect, fused modifier that doesn’t fit standard usage, and leaving out the article a (as in well-known author) is ungrammatical in this position. The correctly hyphenated form, including the article, is the proper choice.