案例分析题When you open a file or run a program in a computer, a window appears on the desktop of your computer. The （） of the window indicates which program you are currently working in arid its color will become blue if a window is active. When you click on The （） , the window disappears and appears as a button on the taskbar. Clicking on a button in （） will invoke a specific command. When you click on The （） , the window disappears and appears as a button on the taskbar.

A. maximize button
B. restore button
C. close button
D. minimize button