The marine biome is a large ecosystem but not larger than some terrestrial ecosystems or is charaby four different zones or had little species or covers a small portion of the earths surface

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.