The correct answer is B Subduction. Subduction is the process by which an oceanic plate gets dragged under another plate and is eventually destroyed in the mantle. Subduction occurs at convergent margins where two oceanic plates collide or an oceanic and Continental plate collide. Oceanic crust is made of mainly of silica and magnesium which is heavier or denser than continental crust which is composed mainly of silica and aluminium.
The subducting plate melts producing excess magma giving rise to volcanoes along these margins.
Researchers found a total of 138 volcanoes in the West Antarctic Ice Sheet overlying the West Antarctic Rift System, 91 of which had never before been identified. Basically they have never seen those types of volcanoes before.
Fossils are the remains of plants and animals that have been preserved for millennia in stones under the Earth's surface. They contain the long chapters of the history of our Earth. Fossils tell us what the earth looked like many millions of years ago, what kind of animals and plants lived on its surface and how it was changing. Fossils show us a history of over a billion years old.
From the fossil from a dry, mountainous area we can conclude that the area was once underwater and over time the soil has risen as result of continental drift and uplift. So, a mountain was once the bottom of a prehistoric ocean or sea.
