Which of the following is an example of a receiver in an event notification service?

In an event notification service, a receiver is a component or an entity that consumes or receives notifications about events. This can take various forms depending on the architecture and the requirements of the application.

A smartphone application serves as a receiver by displaying notifications directly to users on their mobile devices, allowing them to interact with events and updates in real-time. Consequently, users can receive alerts or updates about events through a user-friendly interface.

Email is another common method through which notifications can be sent. In this scenario, emails act as a receiver by allowing users to receive important event updates and information in their inboxes. This method is particularly useful for asynchronous communication, where users may not always be actively monitoring notifications in real time.

An API (Application Programming Interface), on the other hand, enables programmatic access to the event notification service. When an API receives notifications, it serves as an interface for other applications or services to interact with the event data programmatically. This allows developers to build automated processes that can respond to events without manual intervention.

Considering the definitions and use cases for receivers in an event notification service, all the mentioned options—smartphone application, email, and API—effectively serve the role of a receiver by consuming notifications, validating the correctness of