Questions can kill you if you are not ready for them! Be prepared!
You have done a great job and you finish by asking for questions. Someone gives you a killer question and you panic. Suddenly all your hard-won credibility is destroyed because you don’t know how to handle tough questions.
Focus on the questioner. Find out exactly what they want to know. Are they trying to impress their boss or just “bust your chops”? Have they misunderstood something that you have said?
Don’t fake an answer. Tell them you will get back to them with the answer. If someone else knows the answer defer to him. There are entire chapters of presentation skills books that are devoted to the subject of handling tough questions. Buy one and read it.