Possible Clues:

• "Well, duh!"
• "Duh!"
• 'Like, duh!'
• Terse "Well, duh!"
• "Um, of course!"
• Slangy "Duh"
• Curt "Duh"
• Clearly, in a text
• 'Duh!,' in modern slang
• "Duh," in modern slang