Final answer:
During the formation of foliation, the flat minerals are arranged in a parallel alignment due to pressure and high temperatures during the metamorphic process, which causes the minerals to recrystallize or realign perpendicularly to the applied pressures.
Step-by-step explanation:
During the formation of foliation, the flat minerals are arranged in a C) Parallel alignment. Foliation refers to the planar arrangement of mineral grains or structural features within metamorphic rocks. These minerals are typically aligned due to pressure and high temperatures during the metamorphic process, causing them to recrystallize or realign in a direction perpendicular to the pressures applied. In foliated metamorphic rocks, you can find minerals aligned with each other as parallel planes along which the rock can split, by overlapping sheets of minerals such as micas, or by alternating layers of light and dark minerals. This texture contrasts with non-foliated metamorphic rocks, where mineral crystals grow in many directions without any alignment, appearing massive and structureless.