During single line working of DL the speed of the first train is ________ kmph A. 25 B. 20 C. 15 D. None of these

The correct answer is: D. None of these.

During single line working of DL, the speed of the first train is governed by the following factors:

• The length of the train
• The gradient of the track
• The weather conditions
• The type of train
• The driver’s experience

In general, the speed of the first train will be lower than the speed of the second train. This is because the first train has to slow down to allow the second train to pass. The speed of the first train will also be affected by the other factors listed above.

Option A is incorrect because it is the speed of the second train. Option B is incorrect because it is the speed of the first train on a level track. Option C is incorrect because it is the speed of the first train on a downhill track.