A major role of receptors (part of the somatic nervous system) is to help us learn about the environment around us or about the state of our internal environment.

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.

not: both offer magnification to the atomic level.