Cloudcomputingisaphraseusedtodescribeavarietyofcomputingconcepts

Cloudcomputingisaphraseusedtodescribeavarietyofcomputingconceptsthatinvolvealargenumberofcomputers()throughareal-timecommunicationnetworksuchastheInternet.Inscience,cloudcomputingisa()fordistributedcomputingoveranetwork,andmeansthe()torunaprogramorapplicationonmanyconnectedcomputersatthesametime.Thearchitectureofacloudisdevelopedatthreelayers:infrastructure,platform,andapplication.Theinfrastucturelayerisbuiltwithvirtualizedcomputestorageandnetworkresources.Theplatformlay-erisforgeneral-purposeandrepeatedusageofthecollectionofsoftwareresources.TheapplicationlayerisformedwithacollectionofallneededsoftwaremodulesforSaaSapplications.Theinfrastucturelayerservesasthe(请作答此空)forbuildingtheplatformlayerofthecloud.Inturn,theplatformlayerisfounda-tionforimplementingthe()layerforSaaSapplication.

A.network

B.foundation

C.software

D.hardware

正确答案是D