Which component stores application page changes in xml documents and merges the changes during the rendering of the page?

Which component stores application page changes in xml documents and merges the changes
during the rendering of the page?

A.
WebCenter Framework

B.
WebCenter Services

C.
Metadata Services

D.
WebCenter Spaces

E.
Portals

Explanation:
http://docs.oracle.com/cd/E12839_01/webcenter.1111/e10148/jpsdg_files.htm