Do I have to defend the invention patent?

It's not a reply, it's a reply to the review opinion. In most cases, it is necessary, and occasionally it is directly authorized without issuing a review opinion. In the process of patent examination, replying to the examination opinions generally refers to the process of replying to the examination opinions put forward by the examiner in the process of substantive examination of invention patents. In this process, all questions raised in the notice of examination opinions are answered one by one in written form (note that the answers should be based on the contents of the Patent Law and its implementing rules, and there can be no excuses without legal basis). When necessary, the application documents shall be amended, but the scope of the amendment must comply with the provisions of Article 33 of the Patent Law. If the examiner accepts your reply, the patent will have a chance to be authorized. If not, it may give you the next audit opinion again, or directly issue a "rejection notice". In this case, if you want to continue to fight for authorization, you can only fight for authorization by submitting a "review request".