A.
Makes it possible to adjust the focal length like a zoom lens, but requires refocusing after adjusting the focal length.
B.
Allows the depth of field to be adjusted, making it possible to blur out the background for privacy protection or reducing distraction.
C.
Can rapidly change focus between a set of predefined positions, making it easy to move between different points of interest in the scene.
D.
Is a lens where the focus can be adjusted, as opposed to a fixed focus lens, making it possible to focus on objects close to the camera.
