Possible Clues:

• 'Hmm ... doubt it'
• "Hmm ... doubt it"
• "Hmm ... don't think so"
• 'Hmm ... don't think so'
• "Yeah, I doubt it"
• 'Hmm ... I doubt that'
• "Hmm ... I doubt that"
• Hesitant denial
• "That's ... really off the mark"
• 'Don't think so'