You are right, the prepositional phrase in the sentence <em>Late last night there was a loud knock at the door </em>is D) at the door.
The only preposition in the sentence is <em>at, </em>therefore this has to be correct.
You don’t have to worry about picking the right guy or girl because he /she is already picked for you so it’s less stressful
Answer:
All I have to say is that it sounds like a British Karen tbh,idk if this helps or not but yk...
Explanation: