Which of the following is a characteristic of igneous rocks?

Igneous rocks are characterized by their formation from the cooling and solidification of magma or lava. When magma, which is found beneath the Earth's surface, cools and crystallizes, it becomes intrusive igneous rock, such as granite. On the other hand, when lava, which is magma that has reached the surface, cools, it forms extrusive igneous rock, like basalt. This process results in unique textures and mineral compositions that are distinct to igneous rocks, and their formation is a fundamental aspect of the rock cycle.

The other possibilities reflect different geological processes that form other types of rocks. For instance, sediments are involved in the formation of sedimentary rocks, while heat and pressure lead to the formation of metamorphic rocks. Organic processes can result in either sedimentary rocks like coal or biogenic materials but do not pertain to igneous rock formation. Thus, the correct answer emphasizes the unique origins of igneous rocks, which are directly linked to magma or lava.