The correct answer is: A. dispatcher
A dispatcher is a function whose purpose is to send messages to other functions. It is responsible for routing messages to the appropriate destination and ensuring that they are delivered correctly.
A courier is a person who delivers messages or packages. A messenger is a person who carries messages or news. A sender is a person who sends something, such as a letter or package.
In the context of computer programming, a dispatcher is a function that is responsible for routing messages to the appropriate destination. It is typically used in event-driven programming, where events are generated by the user or by other parts of the program. The dispatcher then routes the event to the appropriate handler, which is responsible for processing the event.
For example, in a graphical user interface (GUI), the dispatcher might be responsible for routing mouse clicks to the appropriate widget. When the user clicks on a button, the dispatcher will route the click event to the button’s handler, which will then perform the appropriate action, such as changing the text on the button or opening a new window.
The dispatcher is a critical part of any event-driven program. It ensures that events are handled in a timely and efficient manner.