Which of the Following Best Explains 'Engineering and Make to Order

Which of the following best explains 'engineering and make to order (ETO) '? 

A)  Only raw materials and components are kept in stock. 
B)  All activities are planned based upon customer order. 
C)  There is no stock held at all the purchase and order of materials takes place on the basis of the specific customer order. 
D)  Manufacture takes place based on forecasts and final assembly takes place based on customer orders.