Possible Clues:

• “Everybody knows that!”
• 'It's so obvious!'
• "Like, obviously!"
• "Of course!"
• ''Silly me!''
• Word that punctuates Billie Eilish's 'Bad Guy'
• 'I should've known that!'
• 'Of course ... my bad!'
• 'Obviously, Einstein!'
• “I thought that was obvious!”