Welcome to the Ranch.
The exam "helps" you by indicating how many correct answers are expected. If you tick only 2 out of 3, you won't get any points (if my understanding is correct).
Are you new to programming in general? Or just to Java as a language? The certification exams can be quite tough so allow yourself sufficient time to get a deep understanding of Java and OOP. Luckily there are some great resources available to help you succeed.