Question

How do rivers become larger as they travel across land?

A)Groundwater rises, adding water to rivers.
B)Tributaries combine, adding water to rivers.
C)Ice sheets melt slowly, adding water to rivers.
D)Rainfall in an area increases, adding water to rivers.

Answer 1

B) Tributaries combine, adding water to rivers.

As a river flows downstream, smaller streams and tributaries join it, increasing its volume and discharge (though rainfall and groundwater can also add water, the main reason rivers grow larger downstream is that tributaries merge).