A secure facility uses a pair of infrared devices to detect passage through each of their hallways. The first device emits an infrared beam; the second detects the presence of infrared light. By placing these devices across the hallway, one can detect when the beam is interrupted, indicating some object exists in the space between the emitter and the receiver. In this setup, a sensor will output t a '1' if the beam is unbroken, and a '0' if any object blocks the beam. The facility would like to a system which will produce a logic '1' (indicating that an alarm should sound) if any of three sensors report that a beam is blocked. Which gate would be most appropriate for this task?