The correct answer is: c) Upliftment of the earth’s crust.
The Shillong Plateau is a plateau in northeastern India, covering an area of about 26,000 square kilometers (10,000 square miles). It is located in the state of Meghalaya, and is the highest plateau in India, with an average elevation of 1,500 meters (4,900 feet). The plateau is composed of Precambrian rocks, and is thought to have been formed by the uplift of the earth’s crust.
Volcanic activity is the process by which molten rock, or magma, rises to the surface of the Earth and erupts through a volcano. This process can form mountains, plateaus, and other landforms. However, the Shillong Plateau is not thought to have been formed by volcanic activity.
River erosion is the process by which rivers transport sediment and erode the land. This process can form valleys, canyons, and other landforms. However, the Shillong Plateau is not thought to have been formed by river erosion.
Glacial action is the process by which glaciers move and erode the land. This process can form valleys, fjords, and other landforms. However, the Shillong Plateau is not thought to have been formed by glacial action.
Therefore, the correct answer is: c) Upliftment of the earth’s crust.