Which of the following is an example of an intrusive igneous rock?

Granite is an example of an intrusive igneous rock because it forms from the slow crystallization of magma beneath the Earth’s surface. When magma cools slowly, it allows large mineral crystals to form, creating the coarse-grained texture characteristic of granite. This process typically occurs in large masses known as plutons or batholiths, which can take thousands to millions of years to solidify.

In contrast, other choices like obsidian, basalt, and pumice are examples of extrusive igneous rocks. Obsidian forms quickly from the rapid cooling of lava at the surface, resulting in a glassy texture. Basalt is produced from lava that cools quickly when it erupts on the surface, leading to a fine-grained texture. Pumice similarly forms from volcanic eruptions when lava cools rapidly and traps gas bubbles, producing a light, porous rock. Thus, granite stands out as the only intrusive rock in this set.