A、A section of the railway has got damaged. B、It is too foggy for the driver to see clearly. C、Part of the line is covered with

M：Um, excuse me.Did I just hear that the Preston to Lancaster service has been cancelled again?
W：Well, sir, it won’t be running today.
M：Would that be because of the snow in the Tring Gap?You’ve had three days to get that line clear.
W：Well, actually, sir, the snow melted earlier today and that part of the line’s a foot under water now.And if we did run any trains along there, we’d be having an accident and I’m sure that you wouldn’t...
Q：What is the cause of the train’s delay?