The Information Technology Infrastructure Library (ITIL) consists of five sets of instructional books. Which of the following is considered the core set and focuses on the overall planning of the intended IT services?

A.
Service Operation

B.
Service Design

C.
Service Transition

D.
Service Strategy

Explanation:
D: The fundamental approach of ITIL lies in the creation of Service Strategy, which focuses on the overall planning of the intended IT services. Once the initial
planning has been concluded, the Service Design provides guidelines on designing valid IT services and overall implementation policies. The Service Transition stage is
then initiated, where guidelines regarding evaluation, testing, and validation of the IT services are provided. This allows the transition from business environments into
technology services. The Service Operation makes sure that all the decided services have met their objectives. Finally, the Continual Service Improvement points out
the areas of improvements in the entire service life cycle. The Service Strategy is considered to be the core of ITIL. It consists of a set of guidelines that include best
practices regarding strategy and value planning, design, and alignment between the IT and business approaches, market analysis, service assets, setting targets toward
providing quality service to the clients, and implementation of service strategies.
A is incorrect because Service Operation refers to an important component of the life cycle in which the services are actually delivered. This part of the life cycle
defines a set of guidelines that makes sure that the agreed levels of services are delivered to the customers. The various genres incorporated by Service Operation
include Event Management, Problem Management, Access Management, Incident Management, Application Management, Technical Management, and Operations
Management. Service Operation also balances between the conflicting goals, such as technology vs. business requirements, stability vs. response, cost vs. quality of
service, and reactive vs. proactive activities.
B is incorrect because the Service Design comprises a set of optimal practices for the designing of IT services, including their processes, architectures, policies, and
documentation in order to fulfill the current and future business requirements. The target of the Service Design is to design services according to their agreed business
objectives, design such processes that can support life cycle, identification and management of risks, and involvement in the improvement of IT service quality on a
whole.
C is incorrect because Service Transition focuses on delivering services proposed by business strategy into operational use. It also contains guidelines that enable
the smooth transition of business model into technology services. If the requirements of a service have changed after its design, the Service Transition ensures that
those requirements are delivered according to its modified design. The areas focused on by these guidelines include Transition Planning and Support, Change
Management, Knowledge Management, Release and Deployment Management, Service Validation and Testing, Evaluation, along with the responsibilities of personnel
involved with the Service Transition.