Answer:
A. added introductory words or phrases
Step-by-step explanation:
In the revision of this sentence, the conjunction "and" was removed an introductory word was added: as, which is also subordinating conjunction whose function is to introduce the adverb clause "As Dorian slept under the stars" and connect it to the other clause. This type of revision is often done to give the piece of writing a more natural flow when reading and to convey ideas more clearly.