A. "Once upon a midnight dreary, while I pondered, weak and weary,"
This is the correct answer, because Poe established his mood toward that specific night. Dreary means dull, bleak, and lifeless; depressing, and the whole poem does not detour from that topic when reading past this quote.
"weak and weary"
Poe then makes known of his physical state of being tired and feeble, which can all relate to symptoms of depression, which again, stay all the way throughout the story.