Explanation:

- A (1) "convoy" of trucks carrying soldiers was coming down the mountain road.

- "Convoy" refers to a group of vehicles traveling together.

- The trucks (2) "moved" slowly as there had been heavy snowfall in that area.

- "Moved" is appropriate as it suggests the trucks were traveling or proceeding cautiously.

- Suddenly, with a (3) "crash" a huge tree on the hillside fell...

- "Crash" indicates the loud noise made by the falling tree and debris.

- (4) "Fortunately", the driver of the first truck stopped in time.

- Fortunately" is the correct choice here as it indicates luck or good fortune that prevented an accident.

- The soldiers got down and started (5) "clearing" the road.

- "Clearing" is apt as it refers to removing obstacles from the road.