Question

igneous rocks can be formed from magma that solidifies deep beneath the earth’s surface. when the magma solidifies slowly, it results in rocks with large crystals and a coarse texture. when it cools quickly, it creates more smooth and shiny rock with fine grains. sedimentary rocks are made from the weathering and erosion of pre - existing rocks. if the sediment is buried deeply, it becomes compacted and cemented. sedimentary rocks also form from organic material and often contain fossils. metamorphic rock is a result of a transformation of a pre - existing rock subjected to high heat and pressure. this causes the minerals in the rock to become unstable so they either reorient themselves into layers, giving them a striped look or recrystallize into larger crystals. based on the reading, how would you classify this rock? a sedimentary rock because of its layers. b metamorphic rock because of its stripes. c igneous rock because it has large crystals. d sedimentary because of the presence of fossils.

Explanation:

To classify the rock, we analyze each option:

• Option A: Sedimentary rocks have layers, but the reasoning here doesn't match typical sedimentary rock classification based on layers alone without considering other key features (like fossils or organic material).
• Option B: Metamorphic rocks have stripes (foliation) due to reorientation under heat and pressure. If the rock has stripes, this matches metamorphic rock characteristics.
• Option C: Igneous rocks with large crystals form from slow - cooling magma. The option's reasoning about large crystals is correct for igneous, but we need to check the rock's actual features. However, the question is about classifying based on the given options' reasoning. The description for metamorphic (stripes) is a key identifying feature.
• Option D: Sedimentary rocks with fossils are one type, but the option's reasoning is about presence of fossils, and we need to see which classification matches the rock's features. Since the metamorphic rock's key feature is stripes (from reorientation), option B's reasoning (metamorphic because of stripes) is correct.

Answer:

B. Metamorphic rock because of its stripes.