The correct answer is: D. 09:00.
A caution order is a type of railway safety measure that is used to reduce the risk of accidents. It is typically issued when there is a potential hazard on the railway, such as a track defect or a fallen tree. When a caution order is in place, trains must slow down and proceed with caution.
At stations, caution orders are carried forward from the previous day at 09:00 hours. This means that if a caution order was issued on Sunday, it will remain in place until 09:00 hours on Monday. After 09:00 hours, the stationmaster will assess the situation and decide whether or not to continue the caution order.
The other options are incorrect because they are not the times at which caution orders are carried forward at stations on Monday.