问题：
[单选题] Cloud-computing providers offer their“services”according to differentmodels,which happen to form a stack（ ）,platform as a service(Paas),software as a service(SaaS).A.hardware as A.service(Haas)B.netwo
A、service(IaaS)
B、dat
C、as
D、service(DaaS)
参考答案：
C、as
● 参考解析
