What Are the Obligations of a Processor That Engages a Sub-Processor

What are the obligations of a processor that engages a sub-processor?

A) The processor must give the controller prior written notice and perform a preliminary audit of the sub-processor.
B) The processor must obtain the controller's specific written authorization and provide annual reports on the sub-processor's performance.
C) The processor must receive a written agreement that the sub-processor will be fully liable to the controller for the performance of its obligations in relation to the personal data concerned.
D) The processor must obtain the consent of the controller and ensure the sub-processor complies with data processing obligations that are equivalent to those that apply to the processor.