Identify an example of personification.

Personification is a literary device in which human characteristics are attributed to non-human entities or abstract concepts. In the phrase "The wind whispered through the trees," the wind is given the human ability to "whisper." This creates a vivid image and helps to evoke emotions associated with the way the wind interacts with the trees, making the scene come alive in the reader's imagination.

In contrast, the other examples do not contain personification. "The sky was blue and clear" describes a natural phenomenon without attributing human qualities. "The dog barked loudly" simply states an action performed by a dog, which is human-like but not personification. "The mountain stood tall against the sky" portrays a mountain's physical presence but does not ascribe any human traits to it. Thus, the first option is the clear example of personification among the choices provided.