The mark for review button is an "official" feature that you will see in your actual exam. The button will be there no matter if you are taking the Project Management Professional (PMP), PMI Agile Certified Practitioner (PMI-ACP), or Certified Associate in Project Management (CAPM) Exam. That's why you'll also find it in The PMP Exam Simulator, The PMI-ACP Exam Simulator, and of course The CAPM Exam Simulator. The Mark for Review Button is great for those moments when you wonder "Hmmmm... I think that 'C' is the correct answer but I'm not 100% sure..." In these circumstances you simply select the answer you think is right, click the "Mark" button, and then move on to the next question. The concept behind the button is that it allows you to "flag" any question as you are taking your exam, so that you can return to the question again later for a second look. This is helpful in many circumstance, both when using the simulator as well as on your actual exam .