Which statement is not correct?

a. Data virtualization isolates applications and users from the actual (combinations of) data integration patterns used.

b. Data virtualization extensively uses data consolidation techniques such as ETL.

c. Contrary to a federated database as offered by basic EII, data virtualization does not impose a single data model on top of the heterogeneous data sources.

d. In many real-life contexts, a data integration exercise is an ongoing initiative within an organization, and will often combine a variety of integration strategies and approaches.