The correct answer is A.
OBJ-4.1: Platform as a Service (PaaS) is a cloud computing service that enables consumers to rent fully configured systems that are set up for specific purposes. Platform as a Service (PaaS) provides the end-user with a development environment without all the hassle of configuring and installing it themselves. If you want to develop a customized or specialized program, PaaS helps reduce the development time and overall costs by providing a ready to use platform. Infrastructure as a Service (IaaS) is a cloud computing service that enables a consumer to outsource computing equipment purchases and running their own data center. Software as a Service (SaaS) is a cloud computing service that enables a service provider to make applications available over the Internet to end-users. This can be a calendar, scheduling, invoicing, word processor, database, or other programs. For example, Google Docs and Office 365 are both word processing SaaS solutions. Security as a service is a business model in which a service provider integrates their security services into a corporate infrastructure on a subscription basis more cost-effectively than most individuals or corporations can provide on their own when the total cost of ownership is considered.