Rock formed by the cooling and solidification of magma or lava is called:

Igneous rocks (from the Latin word ignis, meaning "fire") are formed when molten rock material cools and solidifies. Molten rock beneath the Earth's surface is called magma, and when it comes out onto the surface through volcanoes, it is called lava. Igneous rocks are called primary rocks, because all other rocks are ultimately formed from them, and they make up most of the Earth's crust.

Igneous rocks are of two main types, depending on where they form:

Intrusive (plutonic) igneous rocks form when magma cools slowly deep inside the Earth. Because the cooling is slow, large crystals have time to form, so these rocks are coarse-grained. Granite is the best-known example, along with gabbro and diorite. Granite is hard and is widely used for buildings and monuments.

Extrusive (volcanic) igneous rocks form when lava cools quickly on the Earth's surface. Because the cooling is fast, crystals are very small, so these rocks are fine-grained. Basalt is the most common example. Very rapid cooling can produce glassy rock such as obsidian, while frothy lava forms pumice, a light rock full of air holes that can float on water.

Masses of intrusive rock form features such as batholiths, laccoliths, sills and dykes.

In India, the Deccan Trap of the Peninsular Plateau is made largely of basalt formed by huge lava flows about 66 million years ago. The weathering of this basalt has produced the black (regur) soil. Igneous rocks generally do not contain fossils.

Why not the other options?

• ✗Sedimentary rocks form from layers of sediment that are compacted and cemented, such as sandstone and limestone.
• ✗Metamorphic rocks form when existing rocks are changed by heat and pressure, such as marble and slate.
• ✗Organic rocks, such as coal, are a type of sedimentary rock formed from the remains of living things.