Which sensor is specifically designed to respond to activation due to an angle change in fence wire?

The correct choice is the mercury-style switches, as they are specifically designed to detect changes in angle or position, which corresponds to the activation of the fence wire. When the wire on a fence is disturbed or moved, the angle change can cause the mercury within these switches to shift, thereby completing a circuit and indicating an intrusion or disturbance. This functionality makes mercury-style switches particularly suited for security applications, such as monitoring fences.

The other choices serve different purposes. Seismic Point Sensors respond to vibrations or ground movement rather than direct changes in angle or position. Magnetic Vehicle Detection Sensors are intended for detecting the presence of vehicles by sensing magnetic fields, not changes in wire angles. Buckeye Orion Camera Sensors are used for visual surveillance rather than responding to physical changes in a perimeter, such as that of fence wire. Thus, the design and function of mercury-style switches uniquely align with the requirement to respond to angle changes in the context of security fencing.