Answer:

Explanation:

When molten rock cools down and solidifies, it forms igneous rocks. This process occurs when magma or lava, which are molten rocks, cool down and harden.

Process of Formation:
1. Magma Formation: Igneous rocks are formed when the molten rock, known as magma, rises from the Earth's mantle to the surface through volcanic activity or from a magma chamber beneath the surface. Magma is a mixture of molten minerals, gases, and crystals.

2. Temperature and Pressure: As the magma rises towards the surface, it comes in contact with cooler surroundings. The temperature of the magma decreases, causing it to cool down and solidify. The rate of cooling determines the size of the mineral crystals in the rock. Slow cooling results in larger crystals, while rapid cooling leads to smaller crystals or even glassy texture.

3. Crystallization: During the cooling process, the minerals in the magma begin to crystallize and solidify. These minerals are composed of different elements such as silicon, oxygen, aluminum, iron, calcium, and potassium. The specific combination and arrangement of these elements determine the type of igneous rock formed.

4. Types of Igneous Rocks: There are two main types of igneous rocks based on their formation process and mineral composition:
- Intrusive Igneous Rocks: These rocks are formed when magma cools slowly beneath the Earth's surface, allowing enough time for large crystals to form. Some examples of intrusive igneous rocks are granite and gabbro.
- Extrusive Igneous Rocks: These rocks are formed when lava cools rapidly on the Earth's surface or in the atmosphere, resulting in the formation of small crystals or even glassy texture. Examples of extrusive igneous rocks include basalt and obsidian.

Therefore, the correct answer is option 'B' - Igneous rocks.

Igneous rocks is the answer