Answer:
Option b. button
Step-by-step explanation:
Button control is one of the most common user controls in Windows application to enable user perform an immediate action when clicked. We can see there might be more than one button controls in a single Window application and each of them can be used to trigger different specific action.
For example, button control can be created to perform a "Submit" or "Login", or "Calculate" action in Windows application. The button click event will trigger a corresponding action to meet a specific purpose.