Correct Option: B. Basalt Explanation of the Correct Answer Igneous rocks are formed from the solidification of molten rock material, either magma (when it is below the Earth's surface) or lava (when it erupts onto the surface). Basalt is a common type of igneous rock that forms from the rapid cooling of lava at the Earth's surface. It is typically dark in color and has a fine-grained texture due to the quick cooling process, which prevents large crystals from forming. Formation of Basalt: 1. Magma Generation: Basalt originates from the partial melting of the Earth's mantle, which produces magma. 2. Lava Eruption: When this magma reaches the surface through volcanic activity, it is referred to as lava. 3. Cooling and Solidification: As the lava flows and cools quickly upon exposure to air or water, it solidifies into basalt. Basalt is commonly found in oceanic crust and volcanic islands, making it one of the most abundant igneous rocks on Earth. Why the Other Options are Incorrect A. Marble - Type of Rock: Marble is a metamorphic rock, not an igneous rock. It forms from the metamorphism of limestone or dolostone under heat and pressure. - Formation Process: The process involves recrystallization of carbonate minerals, which is entirely different from the cooling and solidification of molten rock. C. Slate - Type of Rock: Slate is also a metamorphic rock. It originates from shale, which undergoes metamorphism due to heat and pressure. - Formation Process: The transformation involves the alignment of clay minerals into a fine-grained texture, which is distinct from the igneous rock formation process. D. Dolomite - Type of Rock: Dolomite is primarily a sedimentary rock, composed mainly of the mineral dolomite (calcium magnesium carbonate). - Formation Process: It forms through the alteration of limestone or through direct precipitation from seawater, which is not related to the cooling of magma or lava. Summary of Key Points

• Igneous Rock Definition: Formed from the cooling and solidification of molten rock (magma/lava).
• Basalt Characteristics: Dark, fine-grained, and commonly found in volcanic regions; it is the correct example of an igneous rock.
• Metamorphic Rocks: Marble and slate are formed from the transformation of existing rocks under heat and pressure, not from molten material.
• Sedimentary Rock: Dolomite is formed from sedimentary processes, not igneous processes.

This understanding of rock types and their formation processes is crucial for students studying agricultural science, especially in areas related to soil formation and geology.