The answer is D. Isaac and Casey are running "like wild horses", therefore this simile emphasizes their passion, fervor, and excitement. Horses are typically beautiful, fast, fortified animals, which further strengthens this idea. Additionally, the word "wild" connotes independence and the vastness associated with long, open meadows. Choices A and B are illogical, as the reader is not directed to contemplate the color or appearance of the wildflowers/carpet. Also, choice C is incorrect considering how the subject of the excerpt is Issac and Casey, not horses.
