Final answer:
Metamorphic rocks are formed when igneous or sedimentary rocks undergo changes in temperature and pressure. Heat and pressure cause minerals in the rock to recrystallize and create a new rock with altered appearance.
Step-by-step explanation:
Metamorphic rocks are formed when igneous or sedimentary rocks undergo changes in temperature and pressure. The factors that contribute to this transformation are a) temperature and pressure. Heat works to soften minerals, allowing ions to migrate in and out of crystal structures, while pressure forces minerals to reorient. These changes in temperature and pressure cause the minerals in the rock to recrystallize, creating a new rock with altered appearance.