Which fuse designation corresponds to the description: Normal switch position route selection relay, northward initiation, "A" end of crossover?

• A. Normal switch position route selection relay, northward initiation, "A" end of crossover.
• B. Normal switch position route selection relay, southward initiation "A" end of crossover.
• C. Low air pressure alarm push button.
• D. Low air pressure alarm stick relay.

Answer: (A)

Understanding fuse designations in signal systems hinges on matching the three encoded elements: the device being energized, the direction of initiation, and the physical location. The description specifies a normal switch position, a route selection relay, initiates in the northward direction, and is located at the A end of a crossover. The designation that exactly reflects all three aspects—normal switch position route selection relay, northward initiation, A end of crossover—fits the description precisely. The other options describe different initiation directions or different devices (like a low air pressure alarm), so they do not align with the given terms.