Final answer:
Sentence (D) showcases correct parallel structure by using a consistent grammatical form in a list, providing clarity and rhythm in the sentence.
Step-by-step explanation:
The sentence that demonstrates correct parallel structure is: D. The human brain consists of billions of cells that enable people to use language, solve problems, and create works of art. In this sentence, the elements in the series (use language, solve problems, and create works of art) are presented in a parallel structure. They are all verbs and maintain a consistent grammatical form, contributing to the clarity and effectiveness of the sentence. Parallel structure is essential for readability and coherence in writing, ensuring that similar ideas are expressed in a consistent manner.