Final answer:
The correct hyphen rule is to hyphenate words acting as one.
Step-by-step explanation:
The correct hyphen rule is to hyphenate words acting as one. When two or more words work together as a single concept or modify a noun, they can be hyphenated to indicate their connection. For example, 'high-quality' and 'well-known' are hyphenated because they are acting as one word to describe a noun. However, it is important to note that not all words acting as one need to be hyphenated, and there are specific guidelines for hyphenating compound words.
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