Answer:
The Battle of Antietam, one of the bloodiest clashes in the conflict, is today considered by scholars to have ended in a stalemate.
Step-by-step explanation:
The appropriate language for an academic journal article should be formal. IN the first, third, and fourth use more casual wording.
For example, the phrases 'kinda unclear', 'all things considered', and 'another dude' are pieces of informal language not appropriate for an informational article.
Only the second sentence uses language formal and knowledgeable enough for an informational article.
So the answer is, 'The Battle of Antietam, one of the bloodiest clashes in the conflict, is today considered by scholars to have ended in a stalemate.'
Good luck ^^