Answer:
B, Seeing the American flag flying above fort McHenry
Step-by-step explanation:
The Star Spangled Banner is based off of the battle of McHenry, lines like "the bombs bursting in air" confirm it was indeed a battle. It was created when Francis Scott Key was watching the battle from his window, and he was focused on looking at if the flag was still there. Originally the Star Spangled Banner was called The Defence of Fort M'Henry