The correct option is B. Igneous Rock. Detailed Explanation

1. Definition of Igneous Rock:
2. 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 (intrusive igneous rocks), or quickly, resulting in small crystals (extrusive igneous rocks).
3. Formation Process:
4. Magma Formation: Magma is generated in the Earth's mantle and crust due to the melting of pre-existing rocks. This can occur due to increased temperature, decreased pressure, or the addition of volatiles (like water).
5. Cooling and Solidification: When magma rises to the surface and erupts as lava, it cools rapidly, forming extrusive igneous rocks like basalt. If magma cools slowly underground, it forms intrusive igneous rocks like granite. The rate of cooling affects the size of the crystals formed in the rock.
6. Examples of Igneous Rocks:
7. Granite: An intrusive igneous rock with large crystals, formed from slow cooling of magma.
8. Basalt: An extrusive igneous rock with small crystals, formed from the rapid cooling of lava.

Why Other Options Are Incorrect

• A. Sedimentary Rock:
• Sedimentary rocks are formed from the accumulation and compaction of mineral and organic particles, or through the precipitation of minerals from water. They do not form from the cooling of magma or lava. Examples include sandstone, limestone, and shale.
• C. Metamorphic Rock:
• Metamorphic rocks are formed from the alteration of existing rocks (igneous, sedimentary, or other metamorphic rocks) due to heat, pressure, or chemically active fluids. This process is called metamorphism and does not involve the cooling of magma or lava. Examples include schist and marble.
• D. Organic Rock:
• Organic rocks are a subset of sedimentary rocks that are formed from the accumulation of plant or animal debris. An example is coal, which is formed from decomposed plant material. Like sedimentary rocks, they do not form from the cooling of magma or lava.

Summary of Key Points

• Igneous rocks are formed from the cooling and solidification of magma or lava.
• They can be classified as intrusive (cooling slowly underground) or extrusive (cooling quickly on the surface).
• Other rock types, such as sedimentary and metamorphic, are formed through different processes and do not involve magma or lava.
• Understanding the rock cycle is crucial for recognizing how different rock types are interrelated.

This thorough understanding of igneous rocks and their formation will help you in your studies of agricultural science, particularly in areas related to soil formation and geology.