Explanation/Reference:
The SOA Service needs to expose process, functionality, and data that is usable in a broader context than the source of the capability was designed to meet. Therefore, creating a SOA Service usually entails some amount of aggregation, transformation, or expansion of existing capabilities provided by the source systems.
Note on D: Each existing application contains its own data model and data formats. This proliferation of data models and data formats is exacerbated by the fact that a single enterprise entity (e.g. customer, product, order) frequently has data elements stored in multiple existing applications. To be successful at exposing existing data via SOA Services, the integration approach must manage this complexity.
Reference: Oracle Reference Architecture, Service-Oriented Integration, Release 3.0