Final answer:
The force of Earth's shifting plates is very powerful, as it is capable of forming mountains by lifting up large pieces of the Earth's crust.
Step-by-step explanation:
Based on the evidence provided that fault block mountains are formed when "pieces of rock are broken off and driven upward by the force of the shifting plates," we can conclude that the force of Earth's shifting plates is very powerful. This force can move continental masses, create extensive mountain ranges, and is responsible for geological phenomena like earthquakes and volcanic activity. These tectonic processes can lift rock structures over time to form prominent features such as the Alps, which were formed as a result of the collision between the African and Eurasian plates.