What is the requirement? A Developer wants to override a button using visualforce on an object.
A. The object record must be instantiated in a controller or extension B. The standardController attribute must be set to the object C. The controller or extension must have a PagerReference Method D. The Action attribute must be set to a controller method
The correct answer to this question is B. When a developer wants to override a button using visualforce on an object, the standardController attribute must be set to the object. In general, a controller is an Apex class which developers use to implement many of the positive features of visualforce, such as its logic.
Standard controllers are often used in coding to provide guidelines for standard functions like delete, save, and create records. Note that if the developer overrides a button there are many other considerations to be considered as to how that override will affect the rest of the system.