Final answer:
The literary device used in the line 'Rough winds do shake the darling buds of May' from Shakespeare's Sonnet 18 is personification.
Step-by-step explanation:
In Shakespeare's Sonnet 18, the line Rough winds do shake the darling buds of May predominantly uses the literary device of personification. Personification is a figurative language technique where human qualities are attributed to objects, animals, or ideas. In this instance, the rough winds are given the human ability to shake, which is not a literal action that the wind can take, but a figurative representation of its effects on the buds of May. This device adds a level of vividness and emotion to the poem by enabling the reader to relate more closely to the natural elements being described.