Question

in these cities, youll see large groups of bikes lined up at sidewalk stations. for a small fee, you can check out a bicycle at one station, ride it, and leave the bike at a different station. bike sharing is great because it lets people ride around without worrying about buying, storing, or repairing their own bikes.
a cyclist chooses a bike at a bike sharing station.
which detail supports the author’s point that bike sharing is great?
you can ride a bike without buying one.
you can ride a bike from one start to another.
you can check out a bike at a library.
you can pick up a bike at a station for free.

Explanation:

The author's point is that bike sharing is great because it lets people ride without buying a bike. The option "You can ride a bike without buying one" directly supports this as it matches the reason given (not worrying about buying, storing, etc.). Other options: "free" isn't stated (the text says "small fee"), "library" is incorrect (stations, not libraries), and "ride from one to another" is about station use but the key point is no need to buy.

Answer:

You can ride a bike without buying one.