The correct answer is: None of these.
The speed of engine movement from traffic yard to loco and loco to traffic yard is not constant. It depends on a number of factors, including the type of engine, the weight of the train, the terrain, and the weather conditions. In general, the speed of engine movement is between 8 and 15 kmph. However, it can be higher or lower depending on the factors mentioned above.
Option A: 8 kmph is a possible speed for engine movement from traffic yard to loco and loco to traffic yard. However, it is not the only possible speed. The speed can be higher or lower depending on the factors mentioned above.
Option B: 10 kmph is a possible speed for engine movement from traffic yard to loco and loco to traffic yard. However, it is not the only possible speed. The speed can be higher or lower depending on the factors mentioned above.
Option C: 15 kmph is a possible speed for engine movement from traffic yard to loco and loco to traffic yard. However, it is not the only possible speed. The speed can be higher or lower depending on the factors mentioned above.
Option D: None of these is the correct answer because the speed of engine movement from traffic yard to loco and loco to traffic yard is not constant. It depends on a number of factors, including the type of engine, the weight of the train, the terrain, and the weather conditions. In general, the speed of engine movement is between 8 and 15 kmph. However, it can be higher or lower depending on the factors mentioned above.