The correct answer is: B. Event procedures.
An event procedure is a subroutine that is executed in response to an event. Events are typically generated by user actions, such as clicking a button or selecting a menu item. Event procedures are defined in the code of the object that is to respond to the event.
Option A is incorrect because operations are not the same as event procedures. Operations are actions that are performed by an object, such as adding a new item to a list or changing the value of a property. Event procedures are executed in response to events, which are typically generated by user actions.
Option C is incorrect because defining events is not the same as writing event procedures. Defining events is the process of specifying the events that an object can respond to. Writing event procedures is the process of creating the code that will be executed in response to an event.
Option D is incorrect because defining actions is not the same as writing event procedures. Defining actions is the process of specifying the actions that will be performed in response to an event. Writing event procedures is the process of creating the code that will be executed in response to an event.