I would be using something like:
/stations/1asca2dac34/distance?from=432dscas
A client starting point could be /stations where he would get a list of all the stations (name, id, geolocation, kind of transports like bus, trains, etc.) that is known by your API.
From there on, by using HATEOAS you could provide the client links to all the underlying resources e.g.:
/stations/{id}/distance?from={id}
And perhaps some other station related stuff:
/stations/{id}/trains/timetable
/stations/{id}/trains/{train_id}/timetable
/stations/{id}/foobar
If you were to start out from /distances is kind of strange, because I for one would not be able to "guess" what kind of list it would return. Let me say up front that none of your options are wrong, but the bottom line is to make it sensible/"guessable" for your client consumer.
Agree with the question what Joshua Moore said. Does a "distances" resource make sense for your consumers or can everything be fanned out from one starting point (e.g. stations) because that is what your API is all/only about?