which methods can you use tointegrate purchase orders within SAP Ariba Buying and invoicing? NOTE: there are 2 correct answers to this question

which methods can you use tointegrate purchase orders within SAP Ariba Buying and invoicing? NOTE: there are 2 correct answers to this question
A . Asynchronous order method
B . Direct order method
C . Indirect order method
D . ERP order method with or without acknowledgment

Answer: B,D