Mountain formation refers to the geological processes that underlie the formation of mountains. These processes are associated with large-scale movements of the Earth's crust (tectonic plates). Folding, faulting, volcanic activity, igneous intrusion and metamorphism can all be parts of the orogenic process of mountain building. The formation of mountains is not necessarily related to the geological structures found on it. They all are formed by the horizontal movement of the plates.

MOUNTAIN BUILDING ACCORDING TO PLATE TECTONIC THEORY

The correct answer for this question is option 'B', which states that mountain building is attributed to horizontal movement of the plates. In order to understand this concept in detail, let's break down the answer into the following sections:

1. Introduction to Plate Tectonic Theory:
The Plate Tectonic Theory is a scientific theory that explains the movement and interaction of the Earth's lithospheric plates. It suggests that the Earth's outer shell is divided into several large and small plates that float on the semi-fluid asthenosphere beneath them.

2. Types of Plate Movements:
There are three main types of plate movements:

- Divergent Boundaries: Plates move apart from each other.
- Convergent Boundaries: Plates move towards each other.
- Transform Boundaries: Plates slide past each other horizontally.

3. Mountain Building:
Mountain building, also known as orogenesis, is a geological process that involves the formation of mountains. This process is closely related to the movement of tectonic plates.

4. Horizontal Movement of Plates and Mountain Building:
The horizontal movement of plates, specifically at convergent boundaries, plays a significant role in mountain building. When two plates collide, the leading edge of one plate is forced beneath the other in a process called subduction.

5. Subduction Zones and Mountain Formation:
Subduction zones are areas where one tectonic plate is being forced beneath another plate. As the subducting plate sinks deeper into the Earth's mantle, it generates intense heat and pressure. This results in the melting of the subducting plate and the overlying mantle, forming a magma chamber.

6. Volcanic Activity and Mountain Formation:
The magma generated in the subduction zone rises to the surface through volcanic activity. This volcanic activity often occurs in the form of explosive eruptions, which lead to the accumulation of volcanic materials such as lava, ash, and pyroclastic debris.

7. Folded Mountain Ranges:
As the volcanic materials accumulate over time, they contribute to the growth of mountain ranges. Additionally, the intense pressure and compression caused by the horizontal movement of plates result in the folding and upliftment of the Earth's crust, creating folded mountain ranges.

8. Examples of Mountain Building:
Some well-known examples of mountain ranges formed by the horizontal movement of plates include the Himalayas, the Andes, and the Rocky Mountains. These mountain ranges are the result of the collision between tectonic plates and the subsequent folding and upliftment of the Earth's crust.

In conclusion, according to the Plate Tectonic Theory, mountain building is attributed to the horizontal movement of the plates. The collision and subduction of plates at convergent boundaries lead to volcanic activity, folding of the Earth's crust, and the formation of mountain ranges.