Describes all the processes associated with the discharge of magma, hot fluids, ash, and gases.

The correct answer is Volcanism. It encompases all volcanic activities which is important because discharge of magma and lava can create new pieces of land or islands, discharge of ash and gasses can poison and destroy communities, and hot fluids, as well as those previously mentioned, can lead to deaths of people. Everyone is familiar with the tragedy of Pompeii that was destroyed and buried because of ash.