The question is, An organization recently moved its custom web application to the cloud and it is obtaining managed services of the back-end...

The question is, An organization recently moved its custom web application to the cloud and it is obtaining managed services of the back-end environment as part of its subscription. Which of the following types of services is this company now using? I've provided the answer choices below and please provide an explanation.

A. SAAS

B. CASB

C. IAAS

D. PAAS