Be authentic, don't act like you know. Admit that is a very tough question. Share your admiration to the inquirer. If you don't know the answer straight -> say it loud. Offer an offline follow-up if the question requires lenghty explanation. Care to touch upon some key aspects in the answer by using storytelling techniques. You don't always need to go every detail. Less is more Verify politely if your feedback provides extensive enough information on the matter

Being caught off guard during a presentation can be challenging, but responding with confidence and authenticity is possible with the right approach. Therefore it is importance take a moment to collect your thoughts. A brief pause can help you regain composure and gives you time to formulate your response. You can also acknowledge the Question or Situation and recognise that being caught off guard is a common experience. A simple acknowledgment, such as "That's a great question," can show that you value audience input and are willing to engage with it. If the question or comment is unclear, don’t hesitate to ask for clarification. This not only buys you time but also ensures you fully understand what is being asked.