The correct answer are: C. heat, and E. pressure.
All metamorphic rocks need this two factors so that they can be formed from either igneous or sedimentary rocks. The metamorphic rocks form deep into the ground where the pressure is higher and the temperature is higher as well, the deeper they form the bigger the pressure and temperature they experience. According to how big of a temperature and how big of a pressure the rocks have been exposed it determines into what type of metamorphic rocks they will turn into, and according to that what kind of a texture and appearance will they have. The amount of time of exposure to heat and pressure is also key to the type and quality of the metamorphic rocks.
A comet is a lump of rock and ice. Spacecraft have flown by comets. A comet only has a tail when it is near the sun. Most comets come from the Kuiper belt. A comet has actually been witnessed hitting a planet. Most comets have short orbital periods.
A comet is a tiny, frozen entity in the Solar System that heats up and starts to emit gases as it approaches the Sun. This process is known as outgassing. This results in an apparent atmosphere or coma, and occasionally a tail as well. These occurrences are caused by how the solar wind and solar radiation interact with the comet's nucleus.
The size of comet nuclei varies between a few hundred meters and tens of kilometers, and they are made up of loose clumps of ice, dust, and tiny rocky particles. A comet's orbit is typically very eccentric and elliptical, and its orbital period can range from a few years to possibly millions of years.
Learn more about Kuiper Belt here:
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<span>the answer is physical boundary</span>
