Advancing glaciers create U-shaped valleys called

A. rias.

B. fjords.

C. aretes.

D. cirques.

The answer is letter b. fjords. U-shaped valleys are formed by mountain glaciers. It creates an inlet when it is filled with ocean water. These valleys are called fjords. Cirque and arête on the other hand, is the starting location for mountain glaciers and the spiky high land between two glaciers which forms a spillway when the glacial action erodes through, respectively.