参考答案：A

解析： 本题考查关于窗口监听器接口中基本方法的知识。选项A正确，window Activated(WindowEvent)方法在窗口激活时被调用到；选项B错误，windowClosed (WindowEvent)方法在窗口已经被关闭时调用；选项C错误，windowOpened(Win dowEvent)方法在窗口已经打开时被调用到；选项D错误，windowDeactivated(Win dowEvent)方法与窗口不再激活时被调用到。故本题答案是A。