A service request is a formal request from a user for something to be provided. Service requests are typically less complex and are either approved or denied based on the budget, need, or urgency.
An emergency change to apply a security patch (A) is not a service request because it is an urgent change that needs to be made to address a security vulnerability. The implementation of a workaround (B) is not a service request because it is a temporary solution to a problem. Managing an interruption to a service (D) is not a service request because it is an incident that needs to be resolved.
Providing a virtual server for a development team (C) is a service request because it is a request for a new service that can be fulfilled by the IT department.