Why can Earth's solid outer layer move even though it is rigid?

A student says, "Tectonic plates are made only of crust." Which response best corrects this statement?

Which sequence best represents how mantle flow can cause plate movement?

Two measuring stations on different tectonic plates move a small distance relative to each other each year. Which explanation agrees with the plate tectonics model?

Which comparison of a tectonic plate and the mantle material below it is most accurate?

Scientists describe tectonic plates as parts of one outer layer rather than as separate pieces of crust alone. What evidence from Earth's structure supports this description?

The diagram shows two sections of Earth's solid outer layer above moving mantle material. Which explanation best accounts for the directions in which the two sections are moving?

In the Earth cross-section, which labelled region represents a complete tectonic plate?

The diagram shows mantle flow beneath a boundary between two plates. Which statement best links the movement in region Y to the movement of the plates?