The answer is "journey". A trip is usually short, enjoyable and includes coming home. There are plenty of clues in the full sentence which indicate the right answer.
I do appreciate Robert's explanation of the other terms. :)
Voyage is usually reserved for travelling over the water, like if you took a ship.
Travel usually means more than a simple plane ride. It usually refers to the entire experience of going places. (Your travels overseas, for example, means more than just the airplane flight. It means all the things you did while you were there.)
Out of all the words, only "trip" can *also* refer to your time spent in one place. For example, let's say that you visit me in Melbourne and stay for a week. When you are about to leave, I might say, "I hope that your trip here was fun." That refers to your time HERE, rather than your time going from one place to another. None of the other words can mean that.
When talking about going from one place to another, "journey" and "trip" are synonyms, but "journey" is much more formal and sounds a bit quaint to me. (I'm American. I don't know what British people would say.)
For the quiz? What's the right answer? I don't know. My guess is that they're looking for "trip."