The correct answer is D. RESTful.
RESTful is an acronym for Representational State Transfer. It is an architectural style for designing and building web services. RESTful services adhere to a set of constraints that make them uniform, stateless, cacheable, and layered. This makes them easy to understand, use, and integrate with other services.
RESTful services are typically accessed using HTTP verbs such as GET, POST, PUT, and DELETE. These verbs are used to perform different actions on resources, such as retrieving a resource, creating a new resource, updating an existing resource, and deleting a resource.
RESTful services are often used to create APIs that allow other applications to interact with them. APIs are a way for two applications to communicate with each other. They are often used to expose data and functionality from one application to another.
RESTful services are a popular choice for building web services because they are easy to understand, use, and integrate with other services. They are also a good choice for building APIs because they are well-defined and follow a set of well-known constraints.
The other options are incorrect because they are not acronyms for Representational State Transfer.