The characteristics of two layers of Earth’s crust are listed.

Layer A: Hard, rigid outermost layer of Earth
Layer B: "Plastic" layer containing the mesosphere

Which statement is true?

Layer A is the crust and Layer B is the mantle.
Layer A is the mantle and Layer B is the crust.
Layer A is the outer core and Layer B is the inner core.
Layer A is the inner core and Layer B is the outer core.