Aservice requestis defined in ITIL 4 as a formal request from a user that initiates an agreed service action. This is typically for things such as access to services, information, or a change in the existing services. It follows a standardized process and is designed to help fulfill routine user needs​​.

Option B, while close, refers to the standardized approach, which is part of the process but not the actual service request.

Option Adescribes the availability of details about service requests, but that does not define the request itself.

Option Drefers to a broader concept of the service request management practice, but not the specific definition of a service request.