They are busy. They are working at a very interesting project.
(Составить 1 Общий вопрос,4 Специальный, Who guestion + вопрос к дополнению) Помогите пожалуйста

1.Are they busy? 2. Who is busy? 3. What are they doing? 
1. Are they working at a very interesting project? 
2. Who is working at a very interesting project?
3. What kind of project they are working at?
4. What are they working at? 
5. What are they doing?