Which is the best way to join sentences 12 and 13?
(12) Outside of cities, there are rough trails. (13) There are
flat surfaces, too.

A. Outside of cities, there are rough trails; flat surfaces, too.

B. Outside of cities, there are rough trails, but flat surfaces, too.

C. Outside of cities, there are rough trails as well as flat surfaces.

D. Outside of cities, there are rough trails, there are flat surfaces, too.