The correct answer is: C. 10
When the train is stopped at FSS for more than 10 minutes, the Driver must send his assistant to station after consulting with guard. This is to ensure that the train is ready to depart and that there are no problems with the track or the train itself.
Option A: 05 is incorrect because the Driver must send his assistant to station after consulting with guard if the train is stopped at FSS for more than 10 minutes, not 5 minutes.
Option B: 07 is incorrect because the Driver must send his assistant to station after consulting with guard if the train is stopped at FSS for more than 10 minutes, not 7 minutes.
Option D: None of these is incorrect because the Driver must send his assistant to station after consulting with guard if the train is stopped at FSS for more than 10 minutes.