If you're trying to add a word to the next sentence it could either be "Although" or "However". The second option sounds better than the first though
"During the shop’s peak hours – from eight in the evening till around midnight – one could hardly hear oneself talk because of the boisterous chatters that went on."
Answer:
The correct answer is D.
Explanation:
A is very informal due to the use of slang such as ''ain't''.
B has an informal tone and language due to the usage of 'you guys' to address other people.
C is very informal due to the use of shortened street slang ''Y'all'' commonly used in informal set-ups for example among friends.