Which of the following are key issues of link state protocols? (Select all that apply.)

A shape is a ____.

A. group where the bottommost layer acts as a mask for all other layers in the group B. vector object that keeps its crisp appearance when resized C. bitmapped object that cannot be moved or copied D. rasterized object that cannot be moved or copied

As shown in the accompanying figure, the red rectangle that appears at the top of the Timeline above the currently displayed frame is the ____________________.

Fill in the blank(s) with the appropriate word(s).