It depends on your educational background. Some of them graduated from informal colleges, and you don't need to reply at all. For example, in some ordinary undergraduate colleges, defense is also necessary, but as long as the answers are similar, teachers generally will not be embarrassed. But I think if you graduated from a regular university, your defense is affirmative, which is also a sign that you have completed your studies. Don't worry too much, it's not as terrible as you think. Come on!