Notice station caution order No. is ________ A. T/409 B. T/B-409 C. T/C-409 D. None of these

The correct answer is: A. T/409

Notice station caution order No. is T/409. It is a notice to all train crews and other personnel working on or near the railroad that there is a potential hazard on the track. The order includes information about the hazard, such as its location, type, and severity, as well as instructions on how to avoid it.

Option B, T/B-409, is not a valid notice station caution order number. Option C, T/C-409, is also not a valid notice station caution order number. Option D, None of these, is also incorrect.