Which of the following is true of Software$-$as$-$a$-$Service $($SaaS$)?$

Select one:

a$.$ It is software that runs in a vendor's data center or in the cloud and it allows selfservice.

b$.$ It is software that kept track of employees and ran reports for human resource managers with support from IT$.$

c$.$ It is software that allowed the human resource unit to run its own reports and make changes with help from IT$.$

d$.$ It is software that runs only in the cloud and allows self$-$service.