Concept:Choosing the correct verb for passengers getting off a train at its final stop.
Explanation:At the terminus, the train reaches its last station, so all passengers must get off.
The verb "alight" is the correct word for leaving a train or bus.
"Disembark" is usually used for leaving a ship or an aircraft, not a train.
"Descend" simply means to go down, which does not fit this context.
"Dismount" is used when getting off a horse or a bicycle.
Therefore, "alight" best matches the action of passengers leaving a train at the terminus.
Answer:A. alight