An igneous rock forms quickly. Which characteristic could the rock have?

A. smooth, sharp texture
B. evidence of folding
C. large mineral crystals
D. small sand grains

C. large mineral crystals

A. smooth, sharp texture

To determine the characteristic of an igneous rock that forms quickly, we need to understand the characteristics of igneous rocks and how they form.

Igneous rocks are formed from the solidification of molten material called magma or lava. The rate at which the magma or lava cools and solidifies influences the characteristics of the resulting igneous rock.

A. Smooth, sharp texture: A smooth, sharp texture in igneous rocks is not typically associated with rocks that form quickly. It suggests that the rock has undergone weathering, erosion, or abrasion processes, which typically occur over long periods of time.

B. Evidence of folding: Folding is a characteristic mostly associated with metamorphic rocks, which are rocks formed due to intense heat and pressure over long periods of time. It is unlikely to find evidence of folding in igneous rocks, especially those that form quickly.

C. Large mineral crystals: Large mineral crystals are generally formed in igneous rocks that cool and solidify slowly. When magma or lava cools slowly, the individual mineral crystals have more time to grow, resulting in larger crystals. Therefore, large mineral crystals are not typically associated with igneous rocks that form quickly.

D. Small sand grains: Small sand grains are commonly found in fine-grained or extrusive igneous rocks. These rocks cool and solidify quickly on or near the Earth's surface. The quick cooling does not allow sufficient time for large crystals to form, resulting in fine-grained rocks with small mineral grains. Therefore, D is the most appropriate characteristic for an igneous rock that forms quickly.

So, the characteristic that an igneous rock formed quickly could have is D. small sand grains.