Had they already arrived when you got there?
The correct option is D: already.
How do you use "Already"?
"Already" is an adverb. When 'has' or 'have' are used as an auxiliary verb, the adverb should be placed after it. For example, The ticket has already been booked. If you use 'has' or 'have' as the main verb, then 'already' comes before it.
For more information about Already, refer to the link:-
brainly.com/question/518189
