The fixed beaconing: Correct
When a vertical signal contradicts a fixed beacon indication, the fixed beacon prevails. Fixed beacons, which are usually static signals (like a warning light or other permanent traffic signals), are typically prioritized over vertical signals (such as traffic lights or signs). The reason for this is that fixed beacons are often used to provide more permanent, important, or safety-related instructions, and they may be designed to override temporary or less significant signals, especially in cases where safety is a concern.
The more restrictive signal: This option is incorrect because while restrictive signals are important for safety, in cases where a vertical signal (like a traffic light) contradicts a fixed beacon, the fixed beacon typically takes precedence.
The vertical signal: This option is also incorrect because vertical signals, such as traffic lights, can be overridden by fixed beacons in some situations.