SAP：有道sap,abap的单选选择题,最好能翻译一下题和答案的内容.1：An IDOC structure is c

SAP：
有道sap,abap的单选选择题,最好能翻译一下题和答案的内容.
1：An IDOC structure is composed of:
Select an answer
A.One substructure,consisting of several fields
B.Several substructures,each made up of several data fields
C.Several segments,each segment having several substructures
D.Several segments,each segment consisting of several data fields