On seeing defective stop signal during train working, Loco Pilot will sound ________ whistle to inform the same. A. One Long Two Short B. Two long one short C. One long one short D. None of these

The correct answer is A. One Long Two Short.

The loco pilot will sound one long and two short whistles to inform the guard of a defective stop signal. This is the standard procedure for informing the guard of a problem, and it allows the guard to take appropriate action to ensure the safety of the train.

Option B is incorrect because it is the wrong number of whistles. Option C is incorrect because it is the wrong order of whistles. Option D is incorrect because it is not a valid option.