正解:B
Video motion detection (VMD) in PTZ (Pan-Tilt-Zoom) cameras is feasible but primarily when the camera is used as a stationary camera. PTZ cameras can activate motion detection when they are not moving, as movement of the camera itself would otherwise trigger the VMD. When the camera is stationary, it can effectively detect motion within its field of view similar to a fixed camera. Therefore, option B is correct. For more detailed information, refer to Axis Communications' guidelines on VMD functionality in PTZ cameras.