What describes the structure of foliated metamorphic rocks?

Foliated metamorphic rocks are characterized by their distinct layered and banded structure, which results from the alignment of mineral grains under directional pressure during the metamorphic process. This foliation occurs as minerals such as mica, chlorite, and others become flattened and aligned along planes. The layers can vary in thickness and composition, reflecting the conditions under which the rock was formed and the types of minerals present. This structural feature is crucial in identifying and classifying metamorphic rocks, as it indicates the history and the geological processes the rock has undergone.

In contrast, the other options do not accurately describe foliated metamorphic rocks. Hard and crystalline refers more to certain igneous or non-foliated metamorphic rocks. A random and jumbled arrangement is typical of non-foliated rocks, where there is no preferred orientation of minerals. Granular and smooth structures are generally observed in rocks that do not exhibit foliation. Thus, the layered and banded nature is what distinctly identifies foliated metamorphic rocks.