The correct answer is personification: "mask thy monstrous visage."
Personification is when an object is given a human-like trait. In this case, the works mask or monstrous, could give human-like qualities. Another example, would be the "lightning danced across the sky." A simile compares two things with like and a metaphor is an implied comparison. Apostrophe in this case means when someone addresses someone not in the poem.