Answer: D) It intensifies the conflict.
Explanation: in literature, a complication is any aspect of a story (a situation or a detail of character ) that the protagonist or antagonist must work through, or resolve in order to move forward. In the given excerpt from "The Strange Case of Dr. Jekyll and Mr. Hyde" by Robert Louis Stevenson, we can see that the complication is the difficulties they had to open the door of Dr. Jekyll's private cabinet, this complication intensifies the conflict of the story.