The correct option is
B. Igneous Rock.
Detailed Explanation
- Definition of Igneous Rock:
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Igneous rocks are formed from the cooling and solidification of molten rock material known as magma (when it is beneath the Earth's surface) or lava (when it erupts onto the surface). This process can occur either slowly, allowing large crystals to form, or quickly, resulting in smaller crystals.
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Formation Process:
- Magma: When magma rises from the Earth's mantle and cools slowly beneath the surface, it forms intrusive igneous rocks (e.g., granite). The slow cooling allows for the growth of large mineral crystals.
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Lava: When lava erupts onto the surface and cools quickly, it forms extrusive igneous rocks (e.g., basalt). The rapid cooling results in a fine-grained texture with small or no visible crystals.
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Types of Igneous Rocks:
- Intrusive Igneous Rocks: Formed from magma that cools slowly underground. Examples include granite and diorite.
- Extrusive Igneous Rocks: Formed from lava that cools quickly on the surface. Examples include basalt and pumice.
Why Other Options Are Incorrect
- A. Sedimentary Rock:
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Sedimentary rocks are formed from the accumulation and compaction of mineral and organic particles, or from the precipitation of minerals from water. They do not form from the cooling of magma or lava. Examples include sandstone, limestone, and shale.
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C. Metamorphic Rock:
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Metamorphic rocks are formed from existing rocks (either igneous, sedimentary, or other metamorphic rocks) that undergo a transformation due to high pressure, high temperature, or chemically active fluids. This process is called metamorphism. Examples include schist and marble. They do not originate from the cooling of magma or lava.
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D. Fossil Rock:
- The term "fossil rock" is not a standard geological classification. It may refer to sedimentary rocks that contain fossils, but it does not describe a type of rock formed from magma or lava. Fossils are typically found in sedimentary rocks, which are formed from the accumulation of sediments, not from molten material.
Summary of Key Points
- Igneous rocks are formed from the cooling and solidification of magma or lava.
- They can be classified into intrusive (cooling slowly underground) and extrusive (cooling quickly on the surface).
- Sedimentary rocks form from the accumulation of sediments, while metamorphic rocks arise from the transformation of existing rocks under heat and pressure.
- The term "fossil rock" is not a recognized geological category and does not pertain to the cooling of magma or lava.
Revision Summary
- Igneous rocks are formed from the cooling of magma or lava.
- Intrusive igneous rocks cool slowly underground; extrusive igneous rocks cool quickly on the surface.
- Sedimentary rocks form from sediments, and metamorphic rocks form from existing rocks under heat and pressure.
- "Fossil rock" is not a standard term in geology.