Which statement is true about stars is correct?
f-star formation begins in a nebula
g- white dwarfs become main-sequence stars when they gain mass
h- supergiants are stars that can absorb black holes
j- main sequence stars are formed by comets

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answer: the metamorphic rocks are formed when they are exposed to high pressure and high temperatures. this happens when one of the earth's plates comes in contact with the other plate by traveling in opposite directions, straight into each other or slipping under one another. the friction that is caused by this activity results in   melting of rocks and when it cools they are known as metamorphic rocks. this process needs a controlled amount of pressure and temperature otherwise it may turn into magma.

causes

fossil fuels burn

cities become more industrialized

human population grows worldwide