Which example demonstrates parallel words?

The correct choice demonstrates parallel words through the use of a similar grammatical structure in its list. In the example "The killer behaved coldly, cruelly, and inexplicably," each adjective describing the killer’s behavior maintains a consistent adverbial form, creating a rhythm that enhances the clarity of the sentence.

Using parallel structure is important in writing because it adds emphasis and improves readability, making ideas clearer and more impactful for readers. The uniformity in "coldly," "cruelly," and "inexplicably" not only emphasizes the nature of the killer's behavior but also creates a more engaging and sophisticated style.

The other options either combine different parts of speech or don't utilize a similar structure effectively. For instance, the first option includes adverbs and adjectives in a way that doesn't maintain consistent form in the list. In the third option, the verbs are not parallel, as "played" and "laughed" do not match the structure of a list. The fourth option mixes adverbial phrases with different forms, leading to a lack of parallelism.