Most rocks form under conditions found a few kilometers under earths surface (no choices, fill in the blank) what are the two main groups of sedimentary rocks? what are three agents of metamorphism? explain the rock cycle by describing how an igneous rock can become a sedimentary rock then a metamorphic rock, and then an igneous rock again.

Most metamorphic processes takes place few kilometers below the Earth's surface. Thus, "metamorphic rocks" are formed under conditions found few kilometers under the Earth's surface.
Sedimentary rocks are formed by the compaction of sediments. Two main groups of sedimentary rocks are clastic sedimentary rocks and chemical sedimentary rocks.
Metamorphism refers to the changes in the mineral composition of the rocks. The three agents of metamorphism are heat, pressure and water.
The conversion of one form of rock to another is referred as rock cycle. In a rock cycle, an igneous rock formed from the deposition of molten magma can get converted into sedimentary rock when igneous rock breaks down into pieces and sediments. Finally, the any sedimentary rock or igneous rock can undergo metamorphosis to form metamorphic rocks. Metamorphic rock can again form igneous rock by melting of magma followed by crystallization.