This is the most challenging among other parts as the questions are more abstract. This is where discussion takes place, an interaction between the examiner and the examinee. This part basically assesses your ability to express your ideas or opinions in an organized, direct, and clearer way.
In this part, the examiner will challenge your answer by disagreeing or asking more follow-up questions and see if you can be flexible enough in defending and explaining your answer further. Actually the examiner does not only rely on the prepared questions written on his sheet, but he can also formulate his own questions based on the answer given by you in order to test your ability to speak your thoughts using the English language.
Questions in this part are actually related to Part 2.