What are the three key technical concepts related to Grid computing?

What are the three key technical concepts related to Grid computing?

A.
Web Services

B.
Server Virtualization

C.
Clustering

D.
Dynamic Provisioning

Explanation:
Grid computing is a technology architecture that virtualizes and pools IT resources,
such as compute power, storage, and network capacity into a set of shared services
that can be distributed and re-distributed as needed. Grid computing involves server
virtualization, clustering, and dynamic provisioning.
Reference: Oracle Reference Architecture, Application Infrastructure Foundation, Release 3.0