He has travelled all over the continent by hitchhiking most of the time.

Answer: Option D

Flying : moving or able to move through the air with wings.
Driving : (of rain or snow) blown by the wind with great force.
Working : having paid employment.
Lift : a free ride in another person's vehicle.
Hitchhiking : travel by getting free lifts in passing vehicles.

Synonym of Hitchhiking is Lift