Answer:
B) un ecosistema
Explanation:
because a river is something that carries life , and it's called an ecosistem
I think also that is b.
a "cascada" is a waterfall
an "ecosistema" it's an ecosistem
a "glaciar" it's a glacial
a "llanura" it's an evenness.
So I think that the best option its an ecosistem, because it have plants and animals.
