The correct answer is: C. 5 kg/cm2 of FP pressure and 4.8 kg/cm2 of BP pressure in the brake van.
The FP pressure is the front pressure, which is the pressure in the brake pipe that is connected to the locomotive. The BP pressure is the brake pipe pressure, which is the pressure in the brake pipe that is connected to the brake van.
The FP pressure must be at least 5 kg/cm2 in order to ensure that the brakes are applied properly. The BP pressure must be at least 4.8 kg/cm2 in order to ensure that the brakes are applied evenly.
If the FP pressure is too low, the brakes may not be applied properly and the train may not stop in time. If the BP pressure is too low, the brakes may not be applied evenly and the train may derail.
It is important to check the FP and BP pressures before starting a passenger train in order to ensure the safety of the passengers and crew.