What must Thomas use to tell the program what to do when the stopwatch is clicked?

• A. Loop
• B. Condition
• C. Function
• D. Event Handler

Answer: (D)

Responding to user actions in a program is handled by an event handler. An event handler is a piece of code registered to run when a specific event occurs, like a click on the stopwatch. It defines what should happen at that moment—starting, stopping, or updating the display. The event handler is the binding that connects the click to the action, and it may call other functions to perform the actual work. A loop would run repeatedly regardless of the click, a condition decides between options inside the flow, and a function is the code that does the work but needs to be invoked by the event handler.