Answer:
en
Step-by-step explanation:
J'aime bien voyager en train means i love to travel by train.
The options:
- J'aime bien voyager dans le train means i love to travel in the train, which is strange wording.
- J'aime bien voyager a train means i love to travel by train, which is right in english but incorrect in french language.
- J'aime bien voyager sur train means i love to travel on train, which sounds like you're literally on top of the train.
- J'aime bien voyager sous le train means i love to travel under the train, which sounds like you want to die lol